Power modules and power converters

Abstract

This disclosure aims to suppress warping of power modules without extensively using ceramic substrates. [Solution] The power module 101 comprises a ceramic substrate 10, a plurality of semiconductor elements, namely diodes 20 and IGBTs 21, mounted on the ceramic substrate 10, an electrode metal plate 61 that joins to the main terminals of the diodes 20 and IGBTs 21, an Invar plate 65 which is a first plate-shaped member having a smaller coefficient of thermal expansion than the electrode metal plate 61 and is positioned across the joint between the electrode metal plate 61 and the diodes 20 and IGBTs 21, and a sealing resin 70 that seals the diodes 20, IGBTs 21, electrode metal plate 61, and Invar plate 65.

Description

Technical Field

[0001] The present disclosure relates to a power module.

Background Art

[0002] In recent years, power modules have been increasingly popular in all products such as industrial equipment, household appliances, or information terminals. In addition to the large amount of heat generated by power modules for handling high voltages and large currents, miniaturization has advanced and the heat generation density is large, so high heat dissipation performance is required.

[0003] [[ID=Is16]]Wide bandgap semiconductors such as SiC have high operating temperatures and excellent efficiency, so they are likely to become the mainstream semiconductor materials for power modules in the future. Therefore, the package form of power modules is required to be applicable to wide bandgap semiconductors.

[0004] With the increasing environmental problems, power modules are becoming more and more popular in all scenarios of electric energy generation, transmission, and regeneration. Power modules used in electric vehicles or household appliances generate a large amount of heat because they handle high voltages and large currents. In addition, power modules are required to be small and lightweight for energy reduction during manufacturing. Therefore, power modules have a large heat generation density and are required to have a structure with excellent heat dissipation performance.

[0005] To enhance the heat dissipation performance of power modules, ceramic substrates are often used as insulating substrates. In addition, wire bonding has been conventionally used for the circuit wiring of the main electrodes of power modules, but in recent years, a method of performing circuit wiring by soldering a copper lead frame with a large current capacity and excellent heat dissipation performance has been increasingly popular.

[0006] When a copper lead frame is connected to the top electrode of a semiconductor element mounted on a ceramic substrate, warping occurs due to the difference in thermal expansion coefficients between the ceramic substrate and the copper lead frame. Furthermore, if resin encapsulation is performed, the warping may become even greater due to the curing shrinkage of the resin or the difference in thermal expansion coefficients.

[0007] Furthermore, when using molds for resin encapsulation, warping can easily cause resin to seep in (burrs).

[0008] Furthermore, if the warping after sealing is temperature-dependent, the gap between the ceramic substrate and the base will change, raising concerns that the joint between the ceramic substrate and the base may be damaged.

[0009] Patent Document 1 describes a method for suppressing warping by eliminating the difference in thermal expansion coefficients and using a ceramic substrate with a metal pattern instead of a copper lead frame for circuit formation. It also describes a configuration that suppresses warping after sealing by placing a ceramic substrate of the same size as the ceramic substrate with a metal pattern in the sealing resin near the upper surface of the module (Figure 5). [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2007-311441 [Overview of the project] [Problems that the invention aims to solve]

[0011] Patent Document 1 discloses two configurations for suppressing warping of a power module: one in which ceramic substrates with metal patterns are placed opposite each other and molded with resin, and another in which a ceramic substrate and a ceramic substrate with a metal pattern are placed opposite each other and molded with resin. However, since it is necessary to use multiple ceramic substrates within the power module, there is a problem of excessive use of ceramic substrates.

[0012] This disclosure was made to solve the above-mentioned problems and aims to suppress warping of power modules without extensive use of ceramic substrates. [Means for solving the problem]

[0013] The power module of this disclosure comprises a ceramic substrate, a plurality of semiconductor elements mounted on the ceramic substrate, an electrode metal plate that joins to the main terminals of the plurality of semiconductor elements, a first plate-shaped member having a smaller coefficient of thermal expansion than the electrode metal plate and positioned across the joint between the electrode metal plate and the plurality of semiconductor elements, and a sealing resin that seals the plurality of semiconductor elements, the electrode metal plate, and the first plate-shaped member. [Effects of the Invention]

[0014] In the power module of this disclosure, a first plate-shaped member having a smaller coefficient of thermal expansion than the electrode metal plate is placed on the side of the electrode metal plate opposite to the ceramic substrate. Therefore, warping of the ceramic substrate caused by the difference in coefficients of thermal expansion between the ceramic substrate and the electrode metal plate and sealing resin is suppressed. In other words, warping of the power module is suppressed without using a large amount of ceramic substrate. [Brief explanation of the drawing]

[0015] [Figure 1] This is a top view of the power module according to Embodiment 1. [Figure 2] This is a cross-sectional view of a power module according to Embodiment 1. [Figure 3] This is a cross-sectional view showing the manufacturing process of a power module according to Embodiment 1. [Figure 4] This is a cross-sectional view showing the manufacturing process of a power module according to Embodiment 1. [Figure 5] This is a cross-sectional view showing the manufacturing process of a power module according to Embodiment 1. [Figure 6] This is a cross-sectional view showing the manufacturing process of a power module according to Embodiment 1. [Figure 7]It is a cross-sectional view showing the manufacturing process of the power module according to Embodiment 1. [Figure 8] It is a cross-sectional view showing the manufacturing process of the power module according to Embodiment 1. [Figure 9] It is a graph showing the warp of the power module according to Embodiment 1. [Figure 10] It is a cross-sectional view showing the warp of the power module according to Embodiment 1. [Figure 11] It is a cross-sectional view of the power module according to Embodiment 2. [Figure 12] It is a top view of the power module according to Embodiment 2. [Figure 13] It is a cross-sectional view showing the manufacturing process of the power module according to Embodiment 2. [Figure 14] It is a cross-sectional view showing the manufacturing process of the power module according to Embodiment 2. [Figure 15] It is a cross-sectional view showing the manufacturing process of the power module according to Embodiment 2. [Figure 16] It is a cross-sectional view showing the manufacturing process of the power module according to Embodiment 2. [Figure 17] It is a cross-sectional view showing the manufacturing process of the power module according to Embodiment 2. [Figure 18] It is a cross-sectional view showing the manufacturing process of the power module according to Embodiment 2. [Figure 19] It is a cross-sectional view of the power module according to the first modification of Embodiment 2. [Figure 20] It is a view showing the warp of the power module according to the first modification of Embodiment 2. [Figure 21] It is a view showing the warp of the power module according to the first modification of Embodiment 2. [Figure 22] It is a cross-sectional view of the power module according to the second modification of Embodiment 2. [Figure 23] It is a cross-sectional view of the power module according to the third modification of Embodiment 2. [Figure 24]This is a cross-sectional view of a power module according to a fourth modified example of Embodiment 2. [Figure 25] This is a cross-sectional view of a power module according to Embodiment 3. [Figure 26] This is a top view of the power module according to Embodiment 3. [Figure 27] This is a top view of the power module according to Embodiment 4. [Figure 28] This is a cross-sectional view of a power module according to Embodiment 4. [Figure 29] This is a cross-sectional view of a power module according to Embodiment 4. [Figure 30] This is a configuration diagram of the power conversion device according to Embodiment 5. [Modes for carrying out the invention]

[0016] The materials and dimensions of the components shown in the following embodiments are illustrative.

[0017] Embodiment 1. Figure 1 is a top view of the power module 101 according to Embodiment 1. Figure 2 is a cross-sectional view of the power module 101.

[0018] As shown in Figures 1 and 2, the power module 101 comprises a base 80, a ceramic substrate 10, a diode 20, an IGBT (Insulated Gate Bipolar Transistor) 21, signal terminals 62, electrode metal plates 61 and 63, an invar plate 65, and a sealing resin 70. Note that in Figure 1, only the external shape of the sealing resin 70 is shown.

[0019] The dimensions of the base 80 are 100mm x 60mm x 3mm thick. The base 80 is made of copper and is nickel-plated.

[0020] A ceramic substrate 10 is joined to the base 80 by solder 31. The ceramic substrate 10 has a structure in which copper conductive layers 12 and 13 are laminated on both sides of a silicon nitride substrate 11. The dimensions of the silicon nitride substrate 11 are 40 mm × 25 mm × 0.32 mm thick. The copper conductive layers 12 and 13 are 0.8 mm thick. The copper conductive layer 13 and the base 80 are joined by solder 31.

[0021] Solder 31 consists of 96.5% tin, 3% silver, and 0.5% copper, and has a melting point of 217°C.

[0022] A diode 20 and an IGBT 21, which serve as power semiconductor elements, are mounted on the ceramic substrate 10 using solder 30. The diode 20 is made of silicon and has dimensions of 14 mm x 9 mm x 0.2 mm thick. The IGBT 21 is made of silicon and has dimensions of 14 mm x 14 mm x 0.2 mm thick.

[0023] Solder 30 is composed of 95% tin and 5% antimony, and has a melting point of 240°C.

[0024] The IGBT21 has an aluminum alloy signal electrode 21s on its upper surface. A signal circuit is formed by connecting the signal electrode 21s and a copper signal terminal 62 with an aluminum wire 40. The wire 40 has a diameter of 0.15 mm. The signal terminal 62 has a width of 1.5 mm and a thickness of 0.6 mm.

[0025] The surface main electrodes (not shown) of the diode 20 and IGBT 21 are made of an aluminum alloy with nickel plating. The surface main electrodes of the diode 20 and IGBT 21 are joined to a copper electrode metal plate 61 with solder 30. The thickness of the electrode metal plate 61 is 0.6 mm. In addition, a copper electrode metal plate 63 is joined to the ceramic substrate 10 to form the main power circuit. The electrode metal plates 61, 63 and the signal terminal 62 are made from the same lead frame and are punched out by press working.

[0026] An Invar plate 65, as a first plate-shaped member, is provided so as to straddle the portion of the electrode metal plate 61 that is mounted on the diode 20 and IGBT 21, that is, the junction of the electrode metal plate 61 with the diode 20 and IGBT 21. In this embodiment, the Invar plate 65 is tightly bonded to the electrode metal plate 61 by solder 30. The Invar plate 65 is a 42 alloy, that is, an alloy of 42% nickel and iron, and its surface is nickel-plated. The dimensions of the Invar plate 65 are 24 mm × 10 mm × 0.5 mm thick.

[0027] An opening 61h with a diameter of 3 mm is formed in the electrode metal plate 61. Similarly, an opening 65h with a diameter of 3 mm is formed in the invar plate 65. The invar plate 65 is positioned so that its opening 65h overlaps with the opening 61h of the electrode metal plate 61. Solder 30 is filled into the openings 61h and 65h.

[0028] The portion of the power module 101 above the ceramic substrate 10 is sealed with a sealing resin 70. The sealing resin 70 is an epoxy resin in which silica filler is dispersed. The electrode metal plates 61, 63 and the signal terminal 62 are exposed from the side of the sealing resin 70, but their tips are bent into an upward direction.

[0029] Figures 3 to 8 are cross-sectional views showing the manufacturing process of the power module 101 according to Embodiment 1.

[0030] As shown in Figure 3, the diode 20 and IGBT 21 are positioned and mounted on the ceramic substrate 10. A sheet of solder 30 is placed between the ceramic substrate 10 and the diode 20 and IGBT 21, and solder bonding is performed using a reflow oven.

[0031] Next, as shown in Figure 4, a copper lead frame, which integrates the electrode metal plate 61 and the signal terminal 62, is positioned and mounted on the diode 20 and IGBT 21. A sheet of solder 30 is placed between the copper lead frame and the diode 20 and IGBT 21 to perform soldering.

[0032] As shown in Figure 5, the signal electrode 21s (not shown) of the IGBT 21 and the signal terminal 62 are connected using wire 40.

[0033] Next, as shown in Figure 6, the Invar plate 65 is mounted so that the opening 65h of the electrode metal plate 61 aligns with the opening 61h of the electrode metal plate 61, and then joined to the electrode metal plate 61 using solder 30.

[0034] As shown in Figure 7, the sealing resin 70 is poured into the mold 71 to perform transfer molding encapsulation.

[0035] Finally, as shown in Figure 8, the electrode metal plate 61 and signal terminal 62 are bent upwards. The copper conductor layer 13 is then joined to the base 80 using solder 31. During this joining process, the module is heated to a temperature that does not melt the solder 30 inside, for example, 235°C.

[0036] Furthermore, all steps in the process shown in Figures 3 to 6, except for the connection using wire 40, can be performed in a single step.

[0037] The base 80 is made of copper, but it may also be made of aluminum with nickel plating in some parts.

[0038] Diode 20 and IGBT 21 are made of silicon, but wide-bandgap semiconductors such as silicon carbide or gallium nitride may be used.

[0039] The composition of solder 30 was set to 95% tin and 5% antimony, with a melting point of 240°C. However, solder 30 may have other compositions as long as its melting point is higher than that of solder 31, and bonding materials with high heat resistance, such as silver sintered material, may also be used.

[0040] The composition of solder 31 was 96.5% tin, 3% silver, and 0.5% copper, with a melting point of 217°C. However, solder 31 may have other compositions as long as the melting point of the solder material is lower than that of solder 30. For example, the composition of solder 31 may be 58% bismuth and 42% tin (melting point 139°C).

[0041] Instead of solder 31, a heat dissipation sheet or thermal grease may be used to join the copper conductor layer 13 and the base 80. However, the higher the thermal conductivity of the heat dissipation sheet, the harder and less deformable it becomes, so delamination is more likely to occur if the module warps at room temperature or if there is a large temperature change due to warping. Also, with thermal grease, there is a concern that the pumping-out phenomenon may occur due to the temperature change of the module's warping, causing it to leak to the outside.

[0042] Although wire 40 is made of aluminum, it may also be made of an aluminum alloy containing trace amounts of additives such as iron, or of copper. Alternatively, instead of wire 40, the signal electrode 21s (not shown) of the IGBT 21 and the signal terminal 62 may be connected by soldering using an aluminum or copper ribbon bond, or a lead frame made of copper or the like.

[0043] The sealing resin 70 may be an epoxy resin with a dispersed Ricafiller, a filler such as alumina, or a mixture of epoxy resin and silicone resin, or a silicone gel. Furthermore, the sealing resin 70 may be a transfer mold type sealing resin or a potting type liquid sealing resin.

[0044] In the above description, the Invar plate 65 and the electrode metal plate 61 were joined using solder 30, but they may also be joined in close contact by adhesive bonding or welding using a laser or the like.

[0045] Although a 42% nickel-iron alloy (thermal expansion coefficient 5 ppm / K) was used for the Invar plate 65, other materials may be used as long as they are metals with lower thermal expansion than copper (thermal expansion coefficient 17 ppm / K). For example, a 36% nickel-iron alloy (thermal expansion coefficient 1.5 ppm / K) or CIC clad material (a laminate of copper / Invar / copper, with a thermal expansion coefficient of 7 ppm / K to 11 ppm / K) may be used for the Invar plate 65.

[0046] Figure 9 is a graph showing the warpage of power module 101 (copper electrodes + Invar plate) compared to a comparative power module (copper electrodes only). Here, as shown in Figure 10, the warpage of the bottom surface of the ceramic substrate 10 was measured at different temperatures before resin encapsulation.

[0047] In Figure 9, the horizontal axis represents temperature (°C), and the vertical axis represents the curvature (μm) of the bottom surface of the ceramic substrate 10. A positive value for the curvature of the bottom surface of the ceramic substrate 10 is indicated by a downward convexity.

[0048] In conventional power modules using only copper electrodes (electrode metal plates 61, 63), the solder used to join the copper electrodes to the semiconductor element has a melting point of 240°C, which is stress-free. As the temperature decreases, the warping increases, reaching approximately 230 μm at room temperature (25°C).

[0049] On the other hand, in the case of a power module in which an Invar plate 65 is bonded to copper electrodes (electrode metal plates 61, 63, 0.6 mm thick), the change in warpage is small because the Invar plate 65 shrinks in the same way as the ceramic substrate 10 even when the temperature drops from the soldering temperature, resulting in a warpage of about 70 μm even at room temperature.

[0050] Although the ceramic substrate 10 inherently has some warping due to the manufacturing process, and therefore the warping is not reduced to zero at the soldering temperature, when comparing the change in warping from room temperature to 225°C, it can be seen that the change is approximately 140 μm when only copper electrodes are used, while the change is significantly reduced to approximately 25 μm when the Invar plate 65 is laminated.

[0051] According to the power module 101 of Embodiment 1, by arranging the Invar plate 65, which is a first plate-shaped member with a small coefficient of thermal expansion, on the opposite side of the electrode metal plate 61 from the ceramic substrate 10, warping caused by the difference in the coefficients of thermal expansion between the ceramic substrate 10 and the electrode metal plate 61, and the difference in the coefficients of thermal expansion between the ceramic substrate 10 and the sealing resin 70, can be suppressed.

[0052] Furthermore, in the power module 101, since the invar plate 65 is tightly bonded to the electrode metal plate 61, the apparent coefficient of thermal expansion of the electrode metal plate 61 is reduced, and warping that occurs between the electrode metal plate 61 and the ceramic substrate 10 is suppressed.

[0053] Furthermore, Invar is suitable as a material for the first plate-shaped member because it has lower thermal expansion, higher rigidity, and is less expensive than copper, which is the material for the electrode metal plate 61.

[0054] Embodiment 2. Figure 11 is a cross-sectional view of the power module 102 according to Embodiment 2. Figure 12 is a top view of the power module 102. Note that in Figure 12, only the outer shapes of the sealing resin 70 and the invar plate 66 are shown.

[0055] The power module 102 differs from the power module 101 according to Embodiment 1 in that it includes an invar plate 66 as a first plate-like member instead of the invar plate 65.

[0056] A spacer 14 is attached to the portion of the electrode metal plate 61 that is mounted on the diode 20 and IGBT 21 using adhesive (not shown), and an invar plate 66 is fixed on top of the spacer 14 using adhesive (not shown). In this way, the invar plate 66 is mounted on the electrode metal plate 61 via the spacer 14, and is positioned above the electrode metal plate 61, spaced apart from it, near the upper surface of the sealing resin 70.

[0057] In addition, the electrode metal plate 61 in the power module 102 does not necessarily need to have an opening 61h.

[0058] According to the power module 102 of Embodiment 2, the invar plate 66 can be positioned closer to a vertically symmetrical position with respect to the ceramic substrate 10, thereby suppressing warping that occurs between the sealing resin 70 and the ceramic substrate 10.

[0059] Spacer 14 is made of copper and is a cube with sides of 2 mm. Invar plate 66 is made of 42 alloy and has dimensions of 46 mm x 12 mm x 1 mm thickness.

[0060] Figures 13 to 18 are cross-sectional views showing the manufacturing process of the power module 102 according to Embodiment 2.

[0061] The processes shown in Figures 13 to 15 are the same as those shown in Figures 3 to 5 described in Embodiment 1, so their explanation will be omitted.

[0062] After the process shown in Figure 15, the Invar plate 66 is bonded to the electrode metal plate 61 with the spacer 14 in between, as shown in Figure 16.

[0063] After the process shown in Figure 16, the processes shown in Figures 17 and 18 are carried out. The processes shown in Figures 17 and 18 are the same as the processes shown in Figures 7 and 8 described in Embodiment 1, so their explanation is omitted.

[0064] Furthermore, all steps in the process shown in Figures 13 to 15, except for the connection using wire 40, can be performed in a single step.

[0065] Figure 19 is a cross-sectional view of a power module 102A according to a first modified example of Embodiment 2. Power module 102A is a combination of power module 101 according to Embodiment 1 and power module 102 according to Embodiment 2. That is, power module 102A includes both an invar plate 65 as a first plate-shaped member joined to an electrode metal plate 61 with solder 30, and an invar plate 66 as a second plate-shaped member mounted on the invar plate 65 via a spacer 14.

[0066] Figure 20 is a graph showing the warpage of power module 102A (with two invar plates) compared to a comparative example power module (without an invar plate). As shown in Figure 21, the warpage of the bottom surface of the ceramic substrate 10 after resin encapsulation was measured.

[0067] As shown in Figure 9, the comparative power module without an Invar plate exhibited a warp of approximately 230 μm at room temperature. However, resin encapsulation increased the warp to 310 μm at room temperature. The warp decreased with increasing temperature, reaching approximately 80 μm at 225°C.

[0068] On the other hand, in the power module 102A having Invar plates 65 and 66, the warpage was about 60 μm at room temperature, and the change in warpage with increasing temperature was small, being about 70 μm at 225°C.

[0069] Figure 22 is a cross-sectional view of a power module 102B according to a second modification of Embodiment 2. Power module 102B differs from power module 102 in that it includes an invar plate 67 as a first plate-like member instead of a spacer 14 and an invar plate 66. In power module 102B, a step is provided in the invar plate 67 by press working, so that the invar plate 67 is provided above the electrode metal plate 61 without a spacer 14. It is also possible to provide a shielding effect to the invar plate 67 by soldering it to the GND layer.

[0070] Figure 23 is a cross-sectional view of a power module 102C according to a third modified example of Embodiment 2. Power module 102C differs from power module 102B in that it includes a corrugated invar plate 68 as a first plate-like member instead of the invar plate 67. The invar plate 68 is formed into a corrugated shape by press working. As a result, the invar plate 68 has a portion that is in close contact with the electrode metal plate 61 and a portion that is located above and away from the electrode metal plate 61. This achieves the effects of Embodiments 1 and 2. An opening 68h is provided in the portion of the invar plate 68 that is in close contact with the electrode metal plate 61, and the opening 68h is arranged to overlap with the opening 61h of the electrode metal plate 61. Solder 30 is filled into these openings 61h and 68h, and the invar plate 68 and the electrode metal plate 61 are joined by the solder 30.

[0071] Figure 24 is a cross-sectional view of a power module 102D according to a fourth modified example of Embodiment 2. Power module 102D differs from power module 102C in that it includes an invar plate 69 as a first plate-shaped member instead of the invar plate 68. The invar plate 69 is U-shaped and has a portion that is in close contact with the electrode metal plate 61 and a portion that is located above and away from the electrode metal plate 61. This achieves the effects of Embodiments 1 and 2. An opening 69h is provided in the portion of the invar plate 69 that is in close contact with the electrode metal plate 61, and the opening 69h is arranged to overlap with the opening 61h of the electrode metal plate 61. Solder 30 is filled into these openings 61h and 69h, and the invar plate 69 and the electrode metal plate 61 are joined by the solder 30. By arranging the opening 69h to overlap with the opening 61h of the electrode metal plate 61, it is also possible to use the opening 69h as a path for supplying the solder 30 for joining.

[0072] With power modules 102C and 102D, a single invar plate 68 or invar plate 69 can suppress both the warping of the ceramic substrate 10 caused by the difference in thermal expansion coefficients with the electrode metal plate 61 and the warping of the ceramic substrate 10 caused by the difference in thermal expansion coefficients with the sealing resin 70.

[0073] Embodiment 3. Figure 25 is a cross-sectional view of the power module 103 according to Embodiment 3. Figure 26 is a top view of the power module 103. In Figure 26, only the outer diameters of the sealing resin 70 and the invar plate 66 are shown.

[0074] The power module 103 differs from the power module 102 according to Embodiment 2 in that it includes an electrode metal plate 90. The electrode metal plate 90 is bonded to the main surface electrodes (not shown) of the diode 20 and IGBT 21 by solder 30. One end of the electrode metal plate 61 is bonded to the upper surface of the electrode metal plate 90, and the other end is exposed from the side surface of the sealing resin 70.

[0075] The electrode metal plate 90 is made of CIC clad material and has dimensions of 24 mm x 10 mm x 0.8 mm thick.

[0076] A copper spacer 14 is attached to the portion of the electrode metal plate 90 that is mounted on the diode 20 and IGBT 21 using adhesive (not shown), and an Invar plate 66, which is a first plate-shaped member similar to that of Embodiment 2, is mounted on top of it and fixed with adhesive (not shown).

[0077] The electrode metal plate 90 made of CIC clad is a metal plate in which Invar is sandwiched between copper, thereby suppressing the total thermal expansion coefficient to approximately 7 ppm / K to 11 ppm / K. Therefore, the electrode metal plate 90 can be selected to have a thermal expansion coefficient close to that of the sealing resin 70 (generally 10 ppm / K to 16 ppm / K). If there are concerns about delamination from the sealing resin 70 due to the large difference in thermal expansion coefficient between Invar and the sealing resin 70, using CIC clad for the electrode metal plate 90 becomes effective.

[0078] Embodiment 4. Figure 27 is a top view of the power module 104 according to Embodiment 4. Figure 28 is a cross-sectional view of the power module 104.

[0079] In the power module 104, the ceramic substrate 10 and the semiconductor element, the semiconductor element and the electrode metal plate 61, and the electrode metal plate 61 and the Invar plate 65 are joined with solder 31 instead of solder 30. The power module 104 also includes a case 50 that houses the ceramic substrate 10, the diode 20, and the IGBT 21, etc. The case 50 is mounted on a base 80. In these respects, the power module 104 differs from the power module 101 according to Embodiment 1.

[0080] The electrode metal plates 61, 63 and the signal terminal 62 are insert-molded into the case 50. That is, the electrode metal plates 61, 63 and the signal terminal 62 are positioned relative to the case 50.

[0081] Figure 29 is a cross-sectional view of a modified power module 104A according to Embodiment 4. Power module 104A differs from power module 104 in that the case 50 is mounted on the ceramic substrate 10 instead of the base 80, and it includes an invar plate 66 as a second plate-shaped member inserted into the case 50. With power module 104A, the height and positioning of the invar plate 66 can be adjusted without using spacers.

[0082] Although the power module 104A shown in Figure 29 includes both an Invar plate 65 as a first plate-like member and an Invar plate 66 as a second plate-like member, it may also include only the Invar plate 66.

[0083] Embodiment 5. This embodiment applies the power module according to Embodiments 1-4 described above to a power converter. The application of the power module according to Embodiments 1-4 is not limited to a specific power converter, but below, as Embodiment 5, we will describe the case in which the power module according to Embodiments 1-4 is applied to a three-phase inverter.

[0084] Figure 30 is a block diagram showing the configuration of a power conversion system to which the power conversion device according to this embodiment is applied.

[0085] The power conversion system shown in Figure 30 consists of a power supply 100, a power converter 200, and a load 300. The power supply 100 is a DC power supply and supplies DC power to the power converter 200. The power supply 100 can be made up of various components, for example, a DC grid, a solar cell, or a battery, or it may be made up of a rectifier circuit or AC / DC converter connected to an AC grid. Alternatively, the power supply 100 may be made up of a DC / DC converter that converts DC power output from a DC grid into a predetermined power.

[0086] The power converter 200 is a three-phase inverter connected between the power supply 100 and the load 300. It converts the DC power supplied from the power supply 100 into AC power and supplies the AC power to the load 300. As shown in Figure 30, the power converter 200 includes a main conversion circuit 201 that converts DC power into AC power and outputs it, and a control circuit 203 that outputs a control signal to the main conversion circuit 201 to control the main conversion circuit 201.

[0087] Load 300 is a three-phase electric motor driven by AC power supplied from power converter 200. Note that Load 300 is not limited to a specific application; it is an electric motor installed in various electrical devices, such as hybrid vehicles, electric vehicles, railway vehicles, elevators, or air conditioning equipment.

[0088] The details of the power converter 200 are described below. The main conversion circuit 201 is equipped with switching elements and freewheeling diodes (not shown), and by switching the switching elements, it converts the DC power supplied from the power supply 100 into AC power and supplies it to the load 300. There are various specific circuit configurations for the main conversion circuit 201, but the main conversion circuit 201 according to this embodiment is a two-level three-phase full-bridge circuit and can be composed of six switching elements and six freewheeling diodes antiparallel to each switching element. Each switching element and each freewheeling diode of the main conversion circuit 201 is composed of a power module from one of the embodiments 1-4 described above. The six switching elements are connected in series in pairs to form upper and lower arms, and each upper and lower arm constitutes each phase (U phase, V phase, W phase) of the full-bridge circuit. The output terminals of each upper and lower arm, i.e., the three output terminals of the main conversion circuit 201, are connected to the load 300.

[0089] Furthermore, the main conversion circuit 201 includes a drive circuit (not shown) for driving each switching element. The drive circuit may be built into the semiconductor module 202, or it may be configured to be a separate drive circuit from the semiconductor module 202. The drive circuit generates a drive signal to drive the switching elements of the main conversion circuit 201 and supplies it to the control electrodes of the switching elements of the main conversion circuit 201. Specifically, according to the control signal from the control circuit 203, which will be described later, it outputs a drive signal to turn on the switching element and a drive signal to turn off the switching element to the control electrodes of each switching element. When the switching element is kept in the ON state, the drive signal is a voltage signal (ON signal) that is greater than or equal to the threshold voltage of the switching element, and when the switching element is kept in the OFF state, the drive signal is a voltage signal (OFF signal) that is less than or equal to the threshold voltage of the switching element.

[0090] The control circuit 203 controls the switching elements of the main converter circuit 201 so that the desired power is supplied to the load 300. Specifically, it calculates the time (on time) that each switching element of the main converter circuit 201 should be in the ON state based on the power to be supplied to the load 300. For example, the main converter circuit 201 can be controlled by PWM control, which modulates the on time of the switching elements according to the voltage to be output. Then, it outputs a control command (control signal) to the drive circuit 202 so that an ON signal is output to the switching elements that should be in the ON state at each point in time, and an OFF signal is output to the switching elements that should be in the OFF state. The drive circuit 202 outputs an ON signal or an OFF signal as a drive signal to the control electrode of each switching element according to this control signal.

[0091] In the power conversion device according to this embodiment, the low-warping power module according to Embodiments 1-4 is used as the switching element and freewheeling diode of the main conversion circuit 201, thereby improving reliability.

[0092] In this embodiment, an example of applying the power module according to Embodiment 1-4 to a two-level three-phase inverter has been described. However, the application of the power module according to Embodiment 1-4 is not limited to this, and it can be applied to various power conversion devices. In this embodiment, a two-level power conversion device is used, but a three-level or multi-level power conversion device may also be used. Furthermore, when supplying power to a single-phase load, the power module according to Embodiment 1-4 may be applied to a single-phase inverter. In addition, when supplying power to a DC load, it is also possible to apply the power module according to Embodiment 1-4 to a DC / DC converter or an AC / DC converter.

[0093] Furthermore, the power conversion device to which the power module according to Embodiments 1-4 is applied is not limited to cases where the load is an electric motor, but can also be used, for example, as a power supply device for an electrical discharge machine, a laser processing machine, an induction heating cooker, or a contactless power supply system, and can even be used as a power conditioner for a solar power generation system or an energy storage system.

[0094] Although preferred embodiments have been described in detail above, the invention is not limited to the above embodiments, and various modifications and substitutions can be made to the above embodiments without departing from the scope of the claims.

[0095] The various aspects of this disclosure are summarized below as an appendix.

[0096] (Note 1) Ceramic substrate and Multiple semiconductor elements mounted on the aforementioned ceramic substrate, An electrode metal plate that is joined to the main terminals of the plurality of semiconductor elements, A first plate-shaped member having a smaller coefficient of thermal expansion than the electrode metal plate is positioned across the junction between the electrode metal plate and the plurality of semiconductor elements, A sealing resin that seals the plurality of semiconductor elements, the electrode metal plate, and the first plate-shaped member, Equipped with, Power module.

[0097] (Note 2) The first plate-shaped member is in close contact with the electrode metal plate. The power module described in Appendix 1.

[0098] (Note 3) The first plate-shaped member is joined to the electrode metal plate via a spacer. The power module described in Appendix 1.

[0099] (Note 4) The present invention further comprises a second plate-shaped member joined to the first plate-shaped member via a spacer, The second plate-shaped member is positioned across the joint between the plurality of semiconductor elements and the electrode metal plate, has a lower coefficient of thermal expansion than the electrode metal plate, and is sealed in the sealing resin. The power module described in Appendix 2.

[0100] (Note 5) The first plate-shaped member has a portion that is joined to the ceramic substrate and a portion that is spaced apart from the electrode metal plate and located above the electrode metal plate. The power module described in Appendix 1.

[0101] (Note 6) The first plate-shaped member has a portion that is in close contact with the electrode metal plate and a portion that is spaced apart from the electrode metal plate and located above the electrode metal plate. The power module described in Appendix 1.

[0102] (Note 7) The first corrugated member is corrugated or U-shaped. The power module described in Appendix 6.

[0103] (Note 8) The electrode metal plate is made of CIC cladding. The power module described in Appendix 3.

[0104] (Note 9) The case further comprises the plurality of semiconductor elements, the electrode metal plate, and the plate-shaped member, The sealing resin is a liquid sealing resin that is filled inside the case. A power module as described in any one of the items from Appendix 1 to Appendix 8.

[0105] (Note 10) The case is mounted on the ceramic substrate, The first plate-shaped member is fixed to the case and is positioned above the electrode metal plate, spaced apart from the electrode metal plate. The power module described in Appendix 9.

[0106] (Note 11) A main conversion circuit having a power module as described in any of Appendix 1 to Appendix 10, which converts the input power and outputs it, A drive circuit that outputs a drive signal to the power module to drive the power module, The system includes a control circuit that outputs a control signal to the drive circuit to control the drive circuit, Power converter. [Explanation of symbols]

[0107] 10 Ceramic substrate, 11 Silicon nitride substrate, 12,13 Copper conductor layer, 14 Spacer, 20 Diode, 21s Signal electrode, 30,31 Solder, 40 Wire, 50 Case, 61 Electrode metal plate, 61h Aperture, 62 Signal terminal, 63 Electrode metal plate, 65,66,67,68,69 Invar plate, 65h Aperture, 68h,69h Aperture, 70 Sealing resin, 71 Mold, 80 Base, 90 Electrode metal plate, 100 Power supply, 101,102,102A,102B,102C,102D,103,104,104A Power module, 200 Power converter, 201 Main converter circuit, 202 Semiconductor module, 203 Control circuit, 300 Load.

Claims

1. Ceramic substrate and Multiple semiconductor elements mounted on the aforementioned ceramic substrate, An electrode metal plate that is joined to the main terminals of the plurality of semiconductor elements, A first plate-shaped member having a smaller coefficient of thermal expansion than the electrode metal plate is positioned across the junction between the electrode metal plate and the plurality of semiconductor elements, The sealing resin that seals the plurality of semiconductor elements, the electrode metal plate, and the first plate-shaped member, Equipped with, Power module.

2. The first plate-shaped member is in close contact with the electrode metal plate. The power module according to claim 1.

3. The first plate-shaped member is joined to the electrode metal plate via a spacer. The power module according to claim 1.

4. The device further comprises a second plate-shaped member joined to the first plate-shaped member via a spacer, The second plate-shaped member is positioned across the joint between the plurality of semiconductor elements and the electrode metal plate, has a lower coefficient of thermal expansion than the electrode metal plate, and is sealed in the sealing resin. The power module according to claim 2.

5. The first plate-shaped member has a portion that is joined to the ceramic substrate and a portion that is spaced apart from the electrode metal plate and located above the electrode metal plate. The power module according to claim 1.

6. The first plate-shaped member has a portion that is in close contact with the electrode metal plate and a portion that is spaced apart from the electrode metal plate and located above the electrode metal plate. The power module according to claim 1.

7. The first corrugated member is corrugated or U-shaped. The power module according to claim 6.

8. The electrode metal plate is made of CIC cladding. The power module according to claim 3.

9. The case further comprises the plurality of semiconductor elements, the electrode metal plate, and the plate-shaped member, The sealing resin is a liquid sealing resin that is filled inside the case. A power module according to any one of claims 1 to 8.

10. The case is mounted on the ceramic substrate, The first plate-shaped member is fixed to the case and is positioned above the electrode metal plate, spaced apart from the electrode metal plate. The power module according to claim 9.

11. A power module according to claim 1, comprising a main conversion circuit that converts and outputs input power, A drive circuit that outputs a drive signal to the power module to drive the power module, The system includes a control circuit that outputs a control signal to the drive circuit to control the drive circuit, Power converter.

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