Semiconductor device

Abstract

A semiconductor device (100) is provided with: a power module (101) having a plurality of semiconductor elements; and a cooler (14) having a cooling surface (20) and thermally connected to the power module (101) via a bonding material (15) having a solder material, the plurality of semiconductor elements being disposed at positions that do not overlap each other when viewed from a direction perpendicular to the cooling surface (20), the cooling surface (20) having a recessed portion (17), and the recessed portion (17) being disposed at positions that do not overlap each other when viewed from the direction perpendicular to the cooling surface (20). The recessed portion (17) is disposed at a position that overlaps with a bonding material (15) provided between the cooling surface (20) and the power module (101) and does not overlap with the plurality of semiconductor elements.

Description

Technical Field

[0001] The present application relates to a semiconductor device. Background Art

[0002] In recent years, semiconductor devices equipped with high-power semiconductor elements have been increasingly being developed with larger capacity. In large-capacity semiconductor devices, in order to pass a large current through the semiconductor element, it is necessary to efficiently transfer the heat generated by the semiconductor element to a cooler. Therefore, in large-capacity semiconductor devices, it is required to reduce the thermal resistance of the bonding material that is provided between the semiconductor element and the cooler and connects the structural components to each other.

[0003] A structure of a semiconductor device that achieves low thermal resistance of a bonding material having a solder material is disclosed (for example, see Patent Document 1). In the structure disclosed in Patent Document 1, a nickel-plated or copper-plated layer is provided on the surface of the power module that is bonded to the cooler to improve solder wettability, thereby achieving improved bonding reliability between the power module and the cooler and low thermal resistance of the bonding material. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent No. 6183556 Summary of the invention Technical problem to be solved by the invention

[0005] In the above-mentioned patent document 1, since a plating layer is provided on the joint surface of the power module, the solder wettability can be improved. In a semiconductor device provided with a plating layer, it is necessary to perform a solder joining process using a formic acid reduction device, or a vacuum solder joining process using a highly active flux. However, in any process, the solder wettability of the joining material having the solder material will deviate. Due to the deviation in the solder wettability generated, solder voids are generated. In particular, when a plating layer is provided, at the temperature at which the solder melts, gas is generated from the organic components contained in the plating layer, and solder voids are formed when the gas is not discharged to the outside. When solder voids are generated between the semiconductor element and the cooler, the cooling of the semiconductor element is hindered by the solder voids, and the thermal resistance increases, so there is a problem of reduced quality of the semiconductor device.

[0006] Therefore, an object of the present application is to obtain a semiconductor device having improved bonding quality of a bonding material including a solder material and lowering thermal resistance. Technical means for solving technical problems

[0007] The semiconductor device disclosed in the present application includes: a power module having multiple semiconductor elements; and a cooler having a cooling surface, and the power module is thermally connected to the cooling surface via a bonding material having a solder material, wherein the multiple semiconductor elements are arranged at positions that do not overlap with each other when viewed in a direction perpendicular to the cooling surface, and the cooling surface has a recessed portion, and the recessed portion is arranged at a position that overlaps with the bonding material provided between the cooling surface and the power module and does not overlap with the multiple semiconductor elements when viewed in a direction perpendicular to the cooling surface. Effects of the Invention

[0008] According to the semiconductor device disclosed in the present application, it includes: a power module having multiple semiconductor elements; and a cooler having a cooling surface, and the power module is thermally connected to the cooling surface via a bonding material having a solder material. When viewed from a direction perpendicular to the cooling surface, the multiple semiconductor elements are arranged at positions that do not overlap with each other, and the cooling surface has a recessed portion, which is arranged at a position that overlaps with the bonding material provided between the cooling surface and the power module and does not overlap with the multiple semiconductor elements. Therefore, when the power module and the cooler are bonded using the bonding material, the recessed portion becomes a path for discharging the gas generated between the power module and the cooler to the outside, which can suppress the generation of pores remaining between the multiple semiconductor elements and the cooler when the bonding material solidifies, thereby improving the bonding quality of the bonding material and achieving low thermal resistance of the bonding material. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a plan view schematically showing the semiconductor device according to the first embodiment. Figure 2 is Figure 1 A cross-sectional view of the semiconductor device cut at the AA cross-sectional position. Figure 3 This is a cross-sectional view schematically showing another semiconductor device according to the first embodiment. Figure 4 This is a cross-sectional view schematically showing a semiconductor device according to the second embodiment. Figure 5 This is a cross-sectional view schematically showing a semiconductor device according to a third embodiment. Figure 6 It is a plan view schematically showing a semiconductor device according to a fourth embodiment. Figure 7 This is a plan view schematically showing a semiconductor device according to the fifth embodiment. Figure 8 is Figure 7 A cross-sectional view of the semiconductor device cut at the BB cross-sectional position. Fig. 9 This is a plan view schematically showing another semiconductor device according to the fifth embodiment. Fig.10 This is a cross-sectional view schematically showing a semiconductor device according to a sixth embodiment. DETAILED DESCRIPTION

[0010] Hereinafter, a semiconductor device according to an embodiment of the present application will be described with reference to the drawings. In each of the drawings, the same or corresponding components and parts are denoted by the same reference numerals for description.

[0011] Implementation method 1. Figure 1 1 is a plan view showing an outline of the semiconductor device 100 according to the first embodiment, in which the sealing resin 13 is shown only in outline. Figure 2 is Figure 1 1 is a cross-sectional view of the semiconductor device 100 cut at the AA cross-sectional position of FIG. The semiconductor device 100 is, for example, a device that converts an input current from a direct current to an alternating current, from an alternating current to a direct current, or converts an input voltage to a different voltage.

[0012] <Semiconductor device 100> like Figure 2 As shown, 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, and the power module 101 is thermally connected to the cooling surface 20 via a bonding material 15 having a solder material. In this way, the power module 101 and the cooler 14 are bonded together to form a semiconductor device 100. Among the plurality of semiconductor elements, one of the two semiconductor elements arranged adjacent to each other is set as a first semiconductor element, and the other is set as a second semiconductor element. In this embodiment, as shown in FIG. Figure 1 As shown, the power module 101 includes first semiconductor elements 1, 2 and second semiconductor elements 5, 6. Thus, the first semiconductor element is formed by two first semiconductor elements 1, 2, and the second semiconductor element is formed by two second semiconductor elements 5, 6, but the present invention is not limited thereto, and the first semiconductor element and the second semiconductor element may each be formed by one semiconductor element.

[0013] <Power Module 101> The power module 101 includes first semiconductor elements 1, 2, a first heat sink 3, second semiconductor elements 5, 6, a second heat sink 7, an insulating material 11, a copper plate 12, and a sealing resin 13. The first semiconductor elements 1, 2 are electrically connected to one surface of the first heat sink 3 via a die bonding material (not shown). The second semiconductor elements 5, 6 are electrically connected to one surface of the second heat sink 7 via a die bonding material (not shown). The second heat sink 7 is arranged at intervals on the same plane as the first heat sink 3. The die bonding material uses, for example, a sintered material composed of solder, Ag nanoparticles, or Cu nanoparticles. Figure 2As shown, one surface of the insulating material 11 is thermally connected to the other surface of the first heat sink 3 and the other surface of the second heat sink 7. One surface of the copper plate 12 is thermally connected to the other surface of the insulating material 11. The sealing resin 13 covers the first heat sink 3, the second heat sink 7, the first semiconductor elements 1 and 2, the second semiconductor elements 5 and 6, and the insulating material 11 in a state where the other surface of the copper plate 12 is exposed. The heat generated when the semiconductor element is operated is sequentially transferred to the chip bonding material, the first heat sink 3 and the second heat sink 7, the insulating material 11, and the copper plate 12, and then transferred to the cooling surface 20 via the bonding material 15, and dissipated from the cooler 14.

[0014] In this embodiment, the power module 101 is in the form of a so-called 2in1 module. Figure 1 As shown, the first semiconductor element 1 and the second semiconductor element 5 as switching elements, and the first semiconductor element 2 and the second semiconductor element 6 as rectifying elements are connected in reverse parallel, and there are two sets of element pairs. The structure of the power module 101 is not limited to this, and the necessary number of first semiconductor elements and second semiconductor elements can be mounted according to the purpose of using the semiconductor device 100.

[0015] The structure of the lead frame of the connection member in the power module 101 is 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 structure of the lead frame is not limited thereto, and when the number of semiconductor elements mounted changes as described above, the structure of the lead frame may be changed according to the number of semiconductor elements mounted.

[0016] One end of the first lead frame 4 is electrically connected to one surface of the first heat sink 3 through a wire bonding material (not shown), and the other end is exposed from the sealing resin 13. The second lead frame 8 is electrically connected to one surface of the first semiconductor element 1, 2 through a chip bonding material (not shown), and is electrically connected to one surface of the second heat sink 7 through a wire bonding material (not shown). One end of the third lead frame 9 is electrically connected to one surface of the second semiconductor element 5, 6 through a chip bonding material (not shown), and the other end is exposed from the sealing resin 13. One end of the fourth lead frame 10 is electrically connected to one surface of the second heat sink 7 through a wire bonding material (not shown), and the other end is exposed from the sealing resin 13. In order to ensure the electrical connection between the lead frame and the heat sink, the wire bonding material is composed of a bonding material having a solder material, for example. The bonding is not limited to the wire bonding material, and metal bonding based on ultrasonic waves or lasers may also be used.

[0017] The details of each component of the power module 101 are described. For the first semiconductor element 1 and the second semiconductor element 5, for example, an IGBT (insulated gate bipolar transistor) or a MOSFET (metal oxide film field effect transistor) is used as a power semiconductor element for power control. In the present embodiment, a structure is adopted in which a switching element without a parasitic diode such as an IGBT is used, and a rectifier element such as a return diode is provided in parallel, but it is not limited to this. An RC-IGBT (reverse conducting IGBT) in which a switching element and a return diode are integrated can also be used. In addition, the following structure can also be adopted: a MOSFET is used, and the parasitic diode of the MOSFET is used as a return diode. In the case of using an RC-IGBT, etc., the first semiconductor element and the second semiconductor element are each composed of one semiconductor element.

[0018] The first semiconductor elements 1, 2 and the second semiconductor elements 5, 6 are formed on a semiconductor substrate made of materials such as silicon, silicon carbide (SiC) or gallium nitride (GaN), and wide bandgap semiconductor elements made of materials such as silicon carbide with a wider bandgap than silicon can be used. When using wide bandgap semiconductor elements, the time change di / dt of the current generated during switching can be made larger than that of elements formed by silicon. In addition, the on-resistance of the wide bandgap semiconductor element is small, the allowable current density is higher, the power loss is lower, and the heat generation is less, so the chip area can be reduced. Since the chip area is reduced, the power module 101 can be miniaturized.

[0019] The first heat sink 3, the second heat sink 7, the first lead frame 4, the second lead frame 8, the third lead frame 9 and the fourth lead frame 10 are made of a metal material having excellent electrical conductivity. Among the metals having excellent electrical conductivity, copper is a particularly preferred material among these materials from the viewpoints of electrical resistance, processability, cost, etc. The copper material here refers to pure copper or a copper alloy having copper as a main component.

[0020] In order to prevent the thermal deformation force caused by the difference in linear expansion coefficient from increasing, the sealing resin 13 preferably uses a resin having a linear expansion coefficient close to the linear expansion coefficients of the first heat sink 3, the second heat sink 7, the first lead frame 4, the second lead frame 8, the third lead frame 9, and the fourth lead frame 10. Therefore, the linear expansion coefficient of pure copper is 16 [ppm / K] to 17 [ppm / K], so the linear expansion coefficient of the sealing resin 13 is also preferably 15 [ppm / K] to 18 [ppm / K]. The sealing resin 13 is an inorganic filler contained in a thermosetting resin such as epoxy resin.

[0021] The insulating material 11 is required to have thermal diffusivity that allows the heat generated when the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6 are operated to be transferred to the cooler 14 and diffused while ensuring electrical insulation between the semiconductor element side and the copper plate 12 side. The insulating material 11 is, for example, a material in which an inorganic filler that is an inorganic filler having high thermal conductivity and insulation is filled in a thermosetting resin, and the first heat sink 3 and the second heat sink 7 are bonded to the copper plate 12 by a thermosetting reaction of the resin. Here, the insulating material 11 is composed of a material having heat dissipation, insulation and adhesion, and has a structure in which an inorganic powder filler such as ceramic particles having high thermal conductivity is contained in a thermosetting resin such as epoxy resin. As an inorganic filler having high thermal conductivity, ceramic particles such as aluminum nitride, silicon nitride, boron nitride, aluminum oxide (alumina), silicon oxide (silicon dioxide), magnesium oxide, zinc oxide, and titanium oxide are preferably used. Any of these inorganic fillers can be used alone, or a plurality of them can be mixed and used.

[0022] <Cooler 14> The cooler 14 that is thermally connected to the power module 101 and the cooling surface 20 requires a high cooling performance. The cooler 14 includes a plurality of heat sinks (not shown) to effectively dissipate the heat transferred from the power module 101. The heat sink is, for example, disposed on a portion of the cooler 14 on the side opposite to the power module 101. The cooler 14 can be any type of cooler of liquid cooling or air cooling. In the present embodiment, the cooler 14 is composed of a metal flat plate radiator, but is not limited thereto, and can also be a liquid cooling cooler having a flow path in which a coolant flows. Preferably, the cooler 14 is formed of any material selected from the group consisting of copper, aluminum, and an alloy of copper or aluminum. In particular, as the material of the cooler 14, aluminum or an alloy containing aluminum, i.e., an aluminum alloy, which is lightweight and has excellent processability, is preferably used. When the material of the cooler 14 is aluminum or an aluminum alloy, the semiconductor device 100 can be made lightweight. In addition, the productivity of the semiconductor device 100 can be improved.

[0023] The other surface exposed from the sealing resin 13 of the copper plate 12 of the power module 101 is thermally connected to the cooling surface 20 of the cooler 14 through the bonding material 15. In order to solder the power module 101 to the cooling surface 20 with high bonding quality through the bonding material 15, higher solder wettability is required for the cooling surface 20 of the cooler 14. Therefore, the material of the cooler 14 is preferably copper with solder wettability. However, as described above, in the case where the material of the main body of the cooler 14 is set to aluminum or an aluminum alloy, a plating 16 with solder wettability is set as the cooling surface 20 of the cooler 14, and copper is preferably used as the material of the plating 16. Instead of directly providing the plating 16 on the aluminum or aluminum alloy, a nickel plating (not shown) may be implemented as a base plating in order to improve the plating adhesion and the solder wettability of the surface.

[0024] In this embodiment, the cooler 14 is made of aluminum or aluminum alloy. Figure 2 As shown, the plating layer 16 is provided on the power module 101 side of the cooler 14. Therefore, the cooling surface 20 is the 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 by the joining material 15, one joint surface is the other surface of the copper plate 12, and the cooling surface 20 as the other joint surface is the plating layer 16 provided on the surface of the cooler 14.

[0025] <Recessed portion 17 of cooling surface 20> The recess 17 of the cooling surface 20, which is the main part of the present application, is described. When viewed from a direction perpendicular to the cooling surface 20, a plurality of semiconductor elements, namely the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6, are arranged at positions that do not overlap with each other. The cooling surface 20 has a recess 17. When viewed from a direction perpendicular to the cooling surface 20, the recess 17 is arranged at a position that overlaps with the bonding material 15 provided between the cooling surface 20 and the power module 101 and does not overlap with the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6. The recess 17 penetrates the plating 16, and the components on the lower side of the plating 16 are exposed. The solder wettability of the exposed lower component is lower than that of the plating 16. The exposed portion of the lower component is the recess surface 18. In the present embodiment, the exposed lower component is aluminum or an aluminum alloy.

[0026] In particular, when the plating layer 16 is provided, gas is generated from the organic component contained in the plating layer 16 at the temperature at which the solder melts, and solder voids are formed when the gas is not discharged to the outside. When solder voids are generated between the semiconductor element and the cooler 14, the cooling of the semiconductor element is hindered by the solder voids, and the thermal resistance increases, thereby reducing the quality of the semiconductor device 100. Such voids are not limited to those generated from the plating layer 16. When the bonding material 15 is melted, when there is a gap between the bonding material 15 and other components, the portion of the gap may become the cause of the generation of voids.

[0027] By providing the recess 17 at a position of the cooling surface 20 that does not overlap with the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6, the recess 17 becomes a path for discharging the gas generated between the power module 101 and the cooler 14 to the outside when the power module 101 and the cooler 14 are bonded by the bonding material 15. Therefore, even if solder voids are generated, the solder voids are discharged to the outside through the recess 17. Since the solder voids are discharged to the outside through the recess 17, the generation of voids remaining between the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6 and the cooler 14 when the bonding material 15 solidifies can be suppressed. Since the generation of voids remaining between the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6 and the cooler 14 is suppressed, the bonding material 15 and the plating layer 16 are filled between the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6 and the cooler 14, thereby improving the bonding quality of the bonding material 15 having the solder material, and achieving low thermal resistance of the bonding material 15. Furthermore, since the space between the first semiconductor elements 1 and 2 and the second semiconductor elements 5 and 6 and the cooler 14 is filled with the bonding material 15 and the plating layer 16 , the heat generated in each semiconductor element can be efficiently transferred to the cooler 14 .

[0028] In the present embodiment, the recess 17 is arranged at a position between the first heat sink 3 and the second heat sink 7 and not overlapping with the first heat sink 3 and the second heat sink 7 when viewed from a direction perpendicular to the cooling surface 20. With such a configuration, since there is no recess 17 between the first heat sink 3 and the second heat sink 7 and the cooler 14, the space between the first heat sink 3 and the second heat sink 7 and the cooler 14 is filled with the bonding material 15 and the plating layer 16, so that the heat generated not only in each semiconductor element but also in each lead frame and each heat sink can be efficiently transferred to the cooler 14. The arrangement of the recess 17 is not limited to this, and the recess 17 can be arranged in other areas as long as the heat transfer hindrance of the recess 17 is suppressed and it does not overlap with the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6. Even when the recess 17 is arranged in other areas, it is possible to achieve low thermal resistance of the bonding material 15 and suppression of solder voids.

[0029] In this embodiment, the exposed lower member is aluminum or aluminum alloy, which has lower solder wettability than the plating layer 16. With this configuration, in the recess 17, since the bonding material 15 and the recess surface 18 are not bonded, a path for discharging gas to the outside can be reliably formed in the recess 17.

[0030] In the present embodiment, the recess 17 is a groove extending to the outside of the bonding material 15 provided between the cooling surface 20 and the power module 101 when viewed from a direction perpendicular to the cooling surface 20. By configuring in this way, since the recess 17 has a portion extending to the outside of the bonding material 15, it is possible to easily discharge gas to the outside. The configuration of the recess 17 is not limited to the structure extending to the outside of the bonding material 15, and it is also possible to configure it only on the inside of the bonding material 15. In the case where the recess 17 is configured on the inside of the bonding material 15, although the gas cannot be discharged to the outside, the gas can be discharged into the recess 17. In addition, in the case where the recess 17 is configured only on the inside of the bonding material 15, it is possible to suppress the intrusion of moisture, foreign matter, etc. from the outside into the inside of the semiconductor device 100 through the recess 17.

[0031] An example of a method for forming the recess 17 in the cooler 14 is described. After the entire cooler 14 is plated with the plating 16, the recess 17 can be formed by cutting away the portion of the plating 16 in the area where the recess 17 is formed. By forming the recess 17 in this way, the recess 17 can be easily formed at a low cost. In the present embodiment, the recess 17 penetrates the plating 16 to expose the components under the plating 16. By using this forming method, the recess 17 can be easily formed, so that the productivity of the semiconductor device 100 can be improved. The method for forming the recess 17 is not limited to this, and a method in which the portion where the recess 17 is to be formed is masked during the plating process and the portion of the cooler 14 other than the portion where the recess 17 is to be formed is plated can also be used.

[0032] In this embodiment, the material of the cooler 14 is aluminum or an aluminum alloy, and a plating layer 16 is provided on the power module 101 side of the cooler 14, but it is not limited to this. The material of the cooler 14 can also be set to copper or a copper alloy, and a plating layer 16 having nickel or tin is provided on the power module 101 side of the cooler 14.

[0033] In addition, when the material of the cooler 14 is copper or copper alloy, Figure 3 As shown, the plating layer 16 may not be provided, and the side of the power module 101 of the copper or copper alloy cooler 14 may be used as the cooling surface 20 , and the recessed portion 17 may be provided on the cooling surface 20 . Figure 3 is a cross-sectional view showing an outline of another semiconductor device 100 according to the first embodiment. Figure 2A cross section of another semiconductor device 100 cut at the same position. In this case, since the plating layer 16 is not provided, no gas is generated from the plating layer 16. However, when the bonding material 15 is melted, if there is a gap between the bonding material 15 and other members, the gap may cause pores to be generated, so such pores can be discharged to the outside from the recess 17. In order to reliably form a pore discharge path in the recess 17, an aluminum layer may be formed on the recess surface 18 of the recess 17 by sputtering or the like.

[0034] As described above, in the semiconductor device 100 of the first embodiment, the power module 101 having the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6 is included; and the cooler 14 having the cooling surface 20, and the power module 101 is thermally connected to the cooling surface 20 via the bonding material 15 having a solder material, the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6 are arranged at positions that do not overlap each other when viewed in a direction perpendicular to the cooling surface 20, and the cooling surface 20 has the recess 17, and the recess 17 is arranged between the cooling surface 20 and the power module 101. The bonding material 15 overlaps with the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6, so when the power module 101 and the cooler 14 are bonded using the bonding material 15, the recess 17 becomes a path for discharging the gas generated between the power module 101 and the cooler 14 to the outside, which can inhibit the generation of pores remaining between the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6 and the cooler 14 when the bonding material 15 solidifies, thereby improving the bonding quality of the bonding material 15 and achieving low thermal resistance of the bonding material 15.

[0035] The power module 101 comprises: a first heat sink 3, first semiconductor elements 1 and 2 are electrically connected to one surface of the first heat sink 3; and a second heat sink 7, the second heat sink 7 is arranged at intervals on the same plane as the first heat sink 3, and second semiconductor elements 5 and 6 are electrically connected to one surface of the second heat sink 7. When viewed from a direction perpendicular to a cooling surface 20, a recess 17 is arranged between the first heat sink 3 and the second heat sink 7 at a position that does not overlap with the first heat sink 3 and the second heat sink 7. In this case, since the recess 17 is not provided between the first heat sink 3 and the second heat sink 7 and the cooler 14, heat generated not only in each semiconductor element but also in each lead frame and each heat sink can be efficiently transferred to the cooler 14.

[0036] The cooling surface 20 is the surface of the plating 16 having solder wettability, and the recess 17 penetrates the plating 16 to expose the components under the plating 16. In this case, the power module 101 and the cooler 14 can be soldered with high bonding quality, and the recess 17 can be easily formed at low cost.

[0037] When the exposed lower member has lower solder wettability than the plating layer 16, since the bonding material 15 and the recess surface 18 are not bonded in the recess 17, a path for discharging gas to the outside can be reliably formed in the recess 17. In addition, when the exposed lower member is aluminum or an aluminum alloy, the semiconductor device 100 can be made lighter and the productivity of the semiconductor device 100 can be improved.

[0038] When viewed from a direction perpendicular to the cooling surface 20, the recess 17 is a groove extending to the outside of the bonding material 15 provided between the cooling surface 20 and the power module 101. In this case, since the recess 17 has a portion extending to the outside of the bonding material 15, the gas can be easily discharged to the outside.

[0039] Implementation method 2. A semiconductor device 100 according to the second embodiment will be described. Figure 4 is a cross-sectional view showing an overview of a semiconductor device 100 according to a second embodiment. Figure 2 A cross-sectional view of the semiconductor device 100 cut at the same position. The semiconductor device 100 according to the second embodiment is configured such that the cross-sectional shape of the recess 17 is different from that of the first embodiment.

[0040] The recess 17 is also formed on the exposed lower member. The recess surface 18 of the recess 17 is provided closer to the cooler 14 side than the portion of the plating layer 16 on the cooler 14 side. By configuring in this way, the cross-sectional area of ​​the recess 17 can be made larger than the cross-sectional area of ​​the recess 17 shown in Embodiment 1. Since the cross-sectional area of ​​the recess 17 is increased, the gas generated when the power module 101 and the cooler 14 are bonded by the bonding material 15 can be more effectively discharged to the outside.

[0041] In the present embodiment, the cross-sectional shape of the recess 17 is a rectangle, but the cross-sectional shape of the recess 17 is not limited to a rectangle. The recess 17 only needs to have a function of a path for discharging the gas generated between the power module 101 and the cooler 14 to the outside, so the cross-sectional shape of the recess 17 may also be a V-shaped or U-shaped shape.

[0042] An example of a method for forming the recess 17 on the cooler 14 is described. After the entire cooler 14 is plated with the plating 16, the recess 17 can be formed by cutting and removing the plating 16 and the portion of the cooler 14 in the area where the recess 17 is formed. By forming the recess 17 in this way, the recess 17 can be easily formed at a low cost. The method for forming the recess 17 is not limited to this, and the following method can also be used: a groove to become the recess 17 is provided in the portion of the cooler 14 where the recess 17 is formed in advance, the portion of the groove to form the recess 17 is masked during the plating process, and the portion of the cooler 14 other than the portion where the recess 17 is formed is plated.

[0043] Implementation method 3. A semiconductor device 100 according to a third embodiment will be described. Figure 5 is a cross-sectional view showing an overview of a semiconductor device 100 according to a third embodiment. Figure 2 A cross-sectional view of the semiconductor device 100 cut at the same position. The semiconductor device 100 according to the third embodiment is configured such that a recess 19 on the module side is provided in a power module 101 .

[0044] The surface of the power module 101 on the bonding material 15 side has a module-side recess 19. The module-side recess 19 is arranged at a position overlapping with the bonding material 15 provided between the cooling surface 20 and the power module 101 and not overlapping with the plurality of semiconductor elements when viewed in a direction perpendicular to the cooling surface 20. In the present embodiment, the module-side recess 19 is arranged between the first semiconductor elements 1, 2 and the second semiconductor elements 5, 6.

[0045] The recessed portion 19 on the module side is a path for discharging the gas generated when the power module 101 and the cooler 14 are bonded together by the bonding material 15 to the outside. By configuring in this way, a path for discharging the gas to the outside can be further provided in addition to the recessed portion 17. Since a path for discharging the gas to the outside is further formed, the gas generated when the power module 101 and the cooler 14 are bonded together can be more effectively discharged to the outside compared to the first embodiment.

[0046] In this embodiment, the module-side recess 19 is provided on the power module 101 side of the recess 17, but the configuration of the module-side recess 19 is not limited thereto. The module-side recess 19 may be further configured at a different position as required. The number of the module-side recess 19 is not limited to one, and a plurality of module-side recesses 19 may be provided.

[0047] In this embodiment, the cross-sectional shape of the recess 19 on the module side is set to be rectangular, but the cross-sectional shape of the recess 19 on the module side is not limited to a rectangular shape. The recess 19 on the module side only needs to have a function of a path for discharging the gas generated between the power module 101 and the cooler 14 to the outside, so the cross-sectional shape of the recess 19 on the module side may also be a V-shaped or U-shaped shape.

[0048] In this embodiment, an example is shown in which the recess 19 on the module side is provided in the semiconductor device 100 shown in Embodiment 1. However, the present invention is not limited to this, and the recess 19 on the module side may be provided in the semiconductor device 100 shown in Embodiment 2.

[0049] Implementation method 4. A semiconductor device 100 according to a fourth embodiment will be described. Figure 6 This is a plan view schematically showing a semiconductor device 100 according to Embodiment 4, in which the sealing resin 13 is shown only in outline and the lead frame is omitted. The semiconductor device 100 according to Embodiment 4 is configured by providing a plurality of semiconductor elements and a plurality of recesses.

[0050] In this embodiment, the power module 101 is a so-called 6-in-1 type power module. Figure 6 In the embodiment, on the upper side, first semiconductor elements 1a, 1b, 1c are arranged on the first heat sink 3 at intervals in the lateral direction of the first heat sink 3, and on the lower side, second semiconductor elements 5a, 5b, 5c are provided on second heat sinks 7a, 7b, 7c, respectively. The first semiconductor elements 1a, 1b, 1c are provided near the center of each portion into which the first heat sink 3 is divided into three in the lateral direction.

[0051] The arrangement of the recessed portion is described. When viewed from a direction perpendicular to the cooling surface 20, the recessed portion 17 is arranged between the first heat sink 3 and the second heat sink 7a, 7b, 7c at a position that does not overlap with the first heat sink 3 and the second heat sink 7a, 7b, 7c. When viewed from a direction perpendicular to the cooling surface 20, the recessed portion 17a is arranged between the second heat sinks 7a, 7b at a position that does not overlap with the second heat sinks 7a, 7b. When viewed from a direction perpendicular to the cooling surface 20, the recessed portion 17b is arranged between the second heat sinks 7b, 7c at a position that does not overlap with the second heat sinks 7b, 7c. When viewed from a direction perpendicular to the cooling surface 20, the recessed portion 17c is arranged between the first semiconductor elements 1a, 1b at a position that does not overlap with the first semiconductor elements 1a, 1b. When viewed from a direction perpendicular to the cooling surface 20, the recessed portion 17d is arranged between the first semiconductor elements 1b, 1c at a position that does not overlap with the first semiconductor elements 1b, 1c.

[0052] In this embodiment, the recessed portion is provided not only between semiconductor elements and between heat sinks, but also between semiconductor elements that are not between heat sinks. Thus, when the semiconductor elements are widely arranged, by providing the recessed portion between semiconductor elements that are not between heat sinks, the gas generated when the power module 101 and the cooler 14 are bonded by the bonding material 15 can be more effectively discharged to the outside.

[0053] The arrangement of the recessed portion is not limited to Figure 6 The configuration shown may be different as long as it overlaps with the bonding material 15 provided between the cooling surface 20 and the power module 101 and does not overlap with the plurality of semiconductor elements when viewed from a direction perpendicular to the cooling surface 20. Even in the case of a different configuration, it is possible to achieve low thermal resistance of the bonding material 15 and suppression of solder voids.

[0054] In the present embodiment, the recesses 17, 17a, 17b, 17c, 17d extend to the outside of the bonding material 15 provided between the cooling surface 20 and the power module 101 when viewed from a direction perpendicular to the cooling surface 20. The arrangement of the recess 17 is not limited to the structure extending to the outside of the bonding material 15, and may be arranged only on the inside of the bonding material 15. In the case where the recesses 17, 17a, 17b, 17c, 17d are arranged on the inside of the bonding material 15, although the gas cannot be discharged to the outside, the gas can be discharged to the inside of the recesses 17, 17a, 17b, 17c, 17d. In addition, in the case where the recesses 17, 17a, 17b, 17c, 17d are arranged only on the inside of the bonding material 15, it is possible to suppress the intrusion of moisture, foreign matter, etc. from the outside into the inside of the semiconductor device 100 through the recesses 17, 17a, 17b, 17c, 17d.

[0055] Implementation method 5. A semiconductor device 100 according to the fifth embodiment will be described. Figure 7 is a plan view schematically showing a semiconductor device 100 according to a fifth embodiment. Figure 8 is Figure 7 BB cross-sectional view of the semiconductor device 100 . The semiconductor device 100 according to the fifth embodiment is configured such that the power module 101 includes the protrusion 21 .

[0056] In this embodiment, if Figure 7As shown, in the outer periphery of the gap between the cooling surface 20 and the power module 101, there is an area where the bonding material 15 is not provided, that is, a non-bonding area 23. When viewed from a direction perpendicular to the cooling surface 20, the recess 17 extends from the area where the bonding material 15 is provided to the non-bonding area 23. In the present embodiment, when viewed from a direction perpendicular to the cooling surface 20, the recess 17 is also provided in a portion of the cooling surface 20 that does not overlap with the power module 101. The power module 101 has a protrusion 21 protruding toward the recess 17 side in the non-bonding area 23. In the present embodiment, one protrusion 21 is provided in each of the two non-bonding areas 23 opposite to the recess 17. A plurality of protrusions 21 may also be provided in each of the non-bonding areas 23.

[0057] like Figure 8 As shown, the protrusion 21 is a portion of the sealing resin 13 that seals the components constituting the power module 101, which protrudes toward the recess 17 side. When the components constituting the power module 101 are sealed, the protrusion 21 is simultaneously produced. The method of producing the protrusion 21 is not limited thereto. For example, a component made of a metal material or the like may be sealed together with the components constituting the power module 101, and the portion protruding from the sealing resin 13 may be used as the protrusion 21. Alternatively, a component that becomes the protrusion 21 may be mounted on a portion of the non-bonding region 23 of the sealing resin 13 that is opposite to the recess 17. The protrusion 21 is made of a metal having high solder wettability. When the protrusion 21 is disposed adjacent to the bonding material 15, the metal and the solder are wetted after the gas is exhausted, thereby suppressing the intrusion of foreign matter such as water into the inner side of the recess 17. When the protrusion 21 is produced simultaneously with the sealing resin 13 when the components constituting the power module 101 are sealed, since other components that become the protrusion 21 are not required, the productivity of the semiconductor device 100 can be improved. Therefore, it is preferable to make the protrusion 21 out of the sealing resin 13 .

[0058] By providing the protrusion 21 in this way, the function of efficiently discharging the gas generated when the power module 101 and the cooler 14 are bonded together by the bonding material 15 to the outside can be maintained, and the intrusion of the cleaning liquid into the space between the power module 101 and the recess 17 in the cleaning process after bonding can be suppressed. By suppressing the intrusion of the cleaning liquid, it is possible to prevent the cleaning liquid from being sprayed out from between the power module 101 and the recess 17 during subsequent drying and adhering to the surface of the power module 101. Since the adhesion of the cleaning liquid to the surface of the power module 101 can be suppressed, the creeping insulation of the power module 101 can be improved.

[0059] exist Figure 7 In the embodiment, the protrusion 21 is arranged at the central portion of the non-bonding region 23 in the direction in which the recess 17 extends, but the arrangement of the protrusion 21 is not limited to the central portion of the non-bonding region 23. Fig. 9As shown, the protrusion 21 may be arranged at the outer end of the non-joining region 23 . Fig. 9 1 is a top view showing an overview of another semiconductor device 100 according to Embodiment 5. By configuring in this way, the area into which the cleaning liquid can penetrate can be reduced, thereby further improving the creepage insulation performance of the power module 101. The closer the protrusion 21 is arranged to the outer end of the non-bonding region 23, the greater the effect of reducing the area into which the cleaning liquid can penetrate.

[0060] In this embodiment, if Figure 8 As shown, the height of the protrusion 21 is greater than the depth of the recess 17, and a gap is provided between the protrusion 21 and the inner side surface of the recess 17. Figure 8 , the cross-sectional shapes of the protrusion 21 and the recess 17 are shown. The intrusion of the cleaning liquid into the space between the power module 101 and the recess 17 can be suppressed by merely providing the protrusion 21. However, when the height of the protrusion 21 is greater than the depth of the recess 17 and a gap is provided between the protrusion 21 and the inner side surface of the recess 17, the effect of suppressing the intrusion of the cleaning liquid can be further improved. As a specific dimension, if the dimension between the top 21a of the protrusion 21 and the bottom 22 of the recess is less than 0.22mm, moisture intrudes but is not discharged to the outside, thereby improving the insulation. If the dimension between the top 21a of the protrusion 21 and the bottom 22 of the recess is less than 0.08mm, the intrusion of moisture can be prevented, thereby achieving a greater effect on improving the insulation.

[0061] In this embodiment, if Figure 8 As shown in the figure, the longitudinal section of the protrusion 21 is a rectangular shape, but the longitudinal section of the protrusion 21 is not limited to a rectangular shape. The protrusion 21 only needs to maintain the function of serving as a path for discharging the gas generated between the power module 101 and the cooler 14 to the outside and have the function of suppressing the intrusion of the cleaning liquid from the outside, so the longitudinal section of the protrusion 21 may be, for example, a V-shaped or U-shaped shape.

[0062] In this embodiment, if Figure 7 As shown, the cross-sectional shape of the protrusion 21 is circular, but the cross-sectional shape of the protrusion 21 is not limited to a circle. The protrusion 21 only needs to maintain the function of being a path for discharging the gas generated between the power module 101 and the cooler 14 to the outside and have the function of inhibiting the intrusion of the cleaning liquid from the outside, so the cross-sectional shape of the protrusion 21 may be, for example, a quadrilateral or hexagonal shape. In the case where the top 21a of the protrusion 21 is arranged on the inner side of the recess 17, the cross-sectional shape of the protrusion 21 is a shape in which the gap between the side wall of the recess 17 and the side wall of the protrusion 21 becomes smaller, and the effect of inhibiting the intrusion of the cleaning liquid can be increased.

[0063] Implementation method 6. A semiconductor device 100 according to a sixth embodiment will be described. Fig.10 is a cross-sectional view showing an overview of a semiconductor device 100 according to a sixth embodiment. Figure 8 A cross-sectional view of the semiconductor device 100 cut at the same position. The semiconductor device 100 according to the sixth embodiment is configured such that the position of the top portion 21 a of the protrusion 21 is defined.

[0064] The top 21a of the protrusion 21 is arranged inside the recess 17, and a gap is provided between the protrusion 21 and the inner side surface of the recess 17. By configuring in this way, the distance between the top 21a of the protrusion 21 and the bottom 22 of the recess can be reduced. Since the distance between the top 21a of the protrusion 21 and the bottom 22 of the recess is reduced, the function as a path for discharging the gas generated between the power module 101 and the cooler 14 to the outside can be maintained, and the effect of suppressing the intrusion of the cleaning liquid can be further improved. Since the effect of suppressing the intrusion of the cleaning liquid is further improved, the creepage insulation of the power module 101 can be further improved.

[0065] In this embodiment, as in the fifth embodiment, the height of the protrusion 21 is greater than the depth of the recess 17, and a gap is provided between the protrusion 21 and the inner side surface of the recess 17, so that the same effect as in the fifth embodiment is achieved. In addition, in this embodiment, the shape of the longitudinal section of the protrusion 21 is a rectangle, but the shape of the longitudinal section of the protrusion 21 is not limited to a rectangle. The shape of the longitudinal section of the protrusion 21 may be, for example, a V-shaped or U-shaped shape.

[0066] In addition, although the present application describes various exemplary embodiments and examples, the various features, methods, and functions described in one or more embodiments are not limited to application to specific embodiments, but may also be applied to the embodiments alone or in various combinations. Therefore, it is considered that numerous modifications not shown in the examples are also included in the technical scope disclosed in the present specification, for example, including the case where at least one component is modified, added or omitted, and the case where at least one component is extracted and combined with components of other embodiments.

[0067] Hereinafter, each aspect of the present disclosure will be collectively described as a supplementary note.

[0068] (Supplementary Note 1) A semiconductor device, comprising: A power module having a plurality of semiconductor elements; and a cooler having a cooling surface, wherein the power module is thermally connected to the cooling surface via a bonding material having a solder material, When viewed in a direction perpendicular to the cooling surface, the plurality of semiconductor elements are arranged at positions that do not overlap each other. The cooling surface has a recessed portion, The recessed portion is arranged at a position overlapping with the bonding material provided between the cooling surface and the power module and not overlapping with the plurality of semiconductor elements when viewed in a direction perpendicular to the cooling surface. (Supplementary Note 2) The semiconductor device according to Supplementary Note 1, characterized in that One of the two adjacently arranged semiconductor elements is used as the first semiconductor element, and the other one is used as the second semiconductor element. The power module has: the first semiconductor element; A first heat sink, wherein the first semiconductor element is electrically connected to a surface of the first heat sink; the second semiconductor element; a second heat sink arranged at intervals on the same plane as the first heat sink, the second semiconductor element being electrically connected to one surface of the second heat sink; an insulating material, the other surface of the first heat sink and the other surface of the second heat sink being thermally connected to one surface of the insulating material; a copper plate, the other side of the insulating material being thermally connected to one side of the copper plate; and a sealing resin covering the first heat sink, the second heat sink, the first semiconductor element, the second semiconductor element, and the insulating material in a state where the other surface of the copper plate is exposed, The recessed portion is disposed at a position between the first heat sink and the second heat sink that does not overlap with the first heat sink and the second heat sink when viewed in a direction perpendicular to the cooling surface. (Supplementary Note 3) The semiconductor device according to Supplementary Note 1 or 2, characterized in that The cooling surface is a surface of a plated layer having solder wettability, The recessed portion penetrates the plating layer, and a member under the plating layer is exposed. (Supplementary Note 4) The semiconductor device according to Supplementary Note 3, characterized in that The exposed lower member has lower solder wettability than the plating layer. (Supplementary Note 5) The semiconductor device according to Supplementary Note 4, characterized in that The exposed lower member is aluminum or an aluminum alloy. (Supplementary Note 6) The semiconductor device according to any one of Supplementary Notes 3 to 5, characterized in that The recessed portion is also formed in the exposed lower member. (Supplementary Note 7) The semiconductor device according to any one of Supplementary Notes 1 to 6, characterized in that The recessed portion is a groove extending to the outside of the bonding material provided between the cooling surface and the power module when viewed in a direction perpendicular to the cooling surface. (Supplementary Note 8) The semiconductor device according to any one of Supplementary Notes 1 to 7, characterized in that The surface of the bonding material side of the power module has a module-side recessed portion, The recessed portion on the module side is arranged at a position overlapping with the bonding material provided between the cooling surface and the power module and not overlapping with the plurality of semiconductor elements when viewed in a direction perpendicular to the cooling surface. (Supplementary Note 9) The semiconductor device according to any one of Supplementary Notes 1 to 7, characterized in that In the outer periphery of the gap between the cooling surface and the power module, there is a non-bonding area where the bonding material is not provided. When viewed in a direction perpendicular to the cooling surface, the recess extends from the region where the bonding material is provided to the non-bonding region. The power module includes a protrusion in the non-bonding region that protrudes toward one side of the recess. (Supplementary Note 10) The semiconductor device according to Supplementary Note 9, characterized in that The height of the protrusion is greater than the depth of the recess, and a gap is provided between the protrusion and an inner side surface of the recess. (Supplementary Note 11) The semiconductor device according to Supplementary Note 9, characterized in that The top of the protrusion is arranged inside the recess, and a gap is provided between the protrusion and the inner side surface of the recess. (Supplementary Note 12) The semiconductor device according to any one of Supplementary Notes 9 to 11, characterized in that The protrusion is arranged at an outer end portion of the non-joining region. Description of symbols

[0069] 1, 1a, 1b, 1c, 2 first semiconductor element, 3 first heat sink, 4 first lead frame, 5, 5a, 5b, 5c, 6 second semiconductor element, 7, 7a, 7b, 7c second heat sink, 8 second lead frame, 9 third lead frame, 10 fourth lead frame, 11 insulating material, 12 copper plate, 13 sealing resin, 14 cooler, 15 bonding material, 16 plating, 17, 17a, 17b, 17c, 17d recess, 18 recess surface, 19 recess on mold side, 20 cooling surface, 21 protrusion, 21a top, 22 bottom of recess, 23 non-bonding area, 100 semiconductor device, 101 power module.

Claims

1. A semiconductor device, characterized in that: include: A power module having a plurality of semiconductor elements; as well as a cooler having a cooling surface, wherein the power module is thermally connected to the cooling surface via a bonding material having a solder material, When viewed in a direction perpendicular to the cooling surface, the plurality of semiconductor elements are arranged at positions that do not overlap each other. The cooling surface has a recessed portion, The recessed portion is arranged at a position overlapping with the bonding material provided between the cooling surface and the power module and not overlapping with the plurality of semiconductor elements when viewed in a direction perpendicular to the cooling surface.

2. The semiconductor device according to claim 1, wherein One of the two semiconductor elements arranged adjacent to each other is used as the first semiconductor element, and the other is used as the second semiconductor element. The power module has: the first semiconductor element; A first heat sink, wherein the first semiconductor element is electrically connected to a surface of the first heat sink; the second semiconductor element; a second heat sink arranged at intervals on the same plane as the first heat sink, the second semiconductor element being electrically connected to one surface of the second heat sink; an insulating material, the other surface of the first heat sink and the other surface of the second heat sink being thermally connected to one surface of the insulating material; a copper plate, the other side of the insulating material being thermally connected to one side of the copper plate; as well as a sealing resin covering the first heat sink, the second heat sink, the first semiconductor element, the second semiconductor element, and the insulating material in a state where the other surface of the copper plate is exposed, The recessed portion is disposed at a position between the first heat sink and the second heat sink that does not overlap with the first heat sink and the second heat sink when viewed in a direction perpendicular to the cooling surface.

3. The semiconductor device according to claim 1 or 2, wherein: The cooling surface is a surface of a plated layer having solder wettability, The recessed portion penetrates the plating layer, and a member under the plating layer is exposed.

4. The semiconductor device according to claim 3, wherein: The exposed lower member has lower solder wettability than the plating layer.

5. The semiconductor device according to claim 4, wherein: The exposed lower member is aluminum or an aluminum alloy.

6. The semiconductor device according to any one of claims 3 to 5, wherein: The recessed portion is also formed in the exposed lower member.

7. The semiconductor device according to any one of claims 1 to 6, wherein: The recessed portion is a groove extending to the outside of the bonding material provided between the cooling surface and the power module when viewed in a direction perpendicular to the cooling surface.

8. The semiconductor device according to any one of claims 1 to 7, wherein: The surface of the bonding material side of the power module has a module-side recessed portion, The recessed portion on the module side is arranged at a position overlapping with the bonding material provided between the cooling surface and the power module and not overlapping with the plurality of semiconductor elements when viewed in a direction perpendicular to the cooling surface.

9. The semiconductor device according to any one of claims 1 to 7, wherein: In the outer periphery of the gap between the cooling surface and the power module, there is a non-bonding area where the bonding material is not provided. When viewed in a direction perpendicular to the cooling surface, the recess extends from the region where the bonding material is provided to the non-bonding region. The power module includes a protrusion in the non-bonding region that protrudes toward one side of the recess.

10. The semiconductor device according to claim 9, wherein: The height of the protrusion is greater than the depth of the recess, and a gap is provided between the protrusion and an inner side surface of the recess.

11. The semiconductor device according to claim 9, wherein The top of the protrusion is arranged inside the recess, and a gap is provided between the protrusion and the inner side surface of the recess.

12. The semiconductor device according to any one of claims 9 to 11, wherein: The protrusion is arranged at an outer end portion of the non-joining region.

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