Semiconductor module, power semiconductor device, method for manufacturing semiconductor module, method for manufacturing power semiconductor device, and power conversion device

Abstract

To obtain a semiconductor module, a power semiconductor device, methods for manufacturing the semiconductor module and the power semiconductor device, and a power conversion device, with which reliability of a junction between the semiconductor module and a cooler can be improved.SOLUTION: An insulating substrate 1 has an insulating plate 1a, a front surface metal pattern 1b formed on a front surface of the insulating plate 1a, and a reverse surface metal pattern 1c formed on a reverse surface of the insulating plate 1a. A semiconductor chip 2 is mounted on the front surface metal pattern 1b of the insulating substrate 1. A main terminal 4 is joined to a main electrode on an upper surface of the semiconductor chip 2. A signal terminal 7a is connected to a control electrode on the upper surface of the semiconductor chip 2 by a wire 8. A sealing resin 9 seals the insulating substrate 1, the semiconductor chip 2, the wire 8, a part of the main terminal 4, and a part of the signal terminal 7a. The reverse surface metal pattern 1c protrudes from a lower surface of the sealing resin 9, and a side surface and a lower surface of the reverse surface metal pattern 1c are exposed from the sealing resin 9. An exposed surface of the reverse surface metal pattern 1c is modified and hardened. The reverse surface metal pattern 1c has a convex shape which bulges downward.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a semiconductor module, a power semiconductor device, a method for manufacturing a semiconductor module, a method for manufacturing a power semiconductor device, and a power conversion device. [Background technology]

[0002] A semiconductor module has been disclosed in which a semiconductor chip is soldered to an insulating substrate, leads are joined to the upper surface of the semiconductor element, and the semiconductor element is resin-sealed by transfer molding (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2014 / 006724 Summary of the Invention [Problem to be solved by the invention]

[0004] Since the semiconductor module is joined to the cooler via heat dissipation grease or solder, it was necessary to improve the reliability of the joint between the semiconductor module and the cooler.

[0005] The present disclosure has been made to solve the problems described above, and its purpose is to provide a semiconductor module, a power semiconductor device, a method for manufacturing a semiconductor module, a method for manufacturing a power semiconductor device, and a power conversion device that can improve the reliability of the joint between the semiconductor module and the cooler. [Means for solving the problem]

[0006] The semiconductor module according to the present disclosure comprises an insulating plate, an insulating substrate having a surface metal pattern formed on a surface of the insulating plate and a back metal pattern formed on a back surface of the insulating plate, a semiconductor chip mounted on the surface metal pattern of the insulating substrate, a main terminal connected to a main electrode on an upper surface of the semiconductor chip, a signal terminal connected by a wire to a control electrode on an upper surface of the semiconductor chip, and a sealing resin that seals the insulating substrate, the semiconductor chip, the wire, a portion of the main terminal, and a portion of the signal terminal, wherein the back metal pattern protrudes from a lower surface of the sealing resin such that the side and lower surfaces of the back metal pattern are exposed from the sealing resin, the exposed surface of the back metal pattern is modified and hardened, and the back metal pattern has a convex shape warped downward.

[0007] a step of connecting a main terminal to a main electrode on an upper surface of the semiconductor chip; a step of connecting a signal terminal to a control electrode on an upper surface of the semiconductor chip by a wire; a step of sealing the insulating substrate, the semiconductor chip, the wire, a portion of the main terminal, and a portion of the signal terminal with a sealing resin; and a step of simultaneously performing a peening treatment on an exposed surface of the back surface metal pattern exposed from a lower surface of the sealing resin and a lower surface of the sealing resin by projecting particles, wherein before the peening treatment, the lower surface of the back surface metal pattern and the lower surface of the sealing resin are flush with each other, and after the peening treatment, the back surface metal pattern protrudes from the lower surface of the sealing resin so that a side surface of the back surface metal pattern is exposed from the sealing resin, the exposed surface of the back surface metal pattern that has been peened is modified and hardened, and the back surface metal pattern that has been peened has a convex shape that is warped downward. Effect of the Invention

[0008] In the present disclosure, the rear metal pattern protrudes from the lower surface of the sealing resin, the side and lower surfaces of the rear metal pattern are exposed from the sealing resin, the exposed surface of the rear metal pattern is modified and hardened, and the rear metal pattern has a downwardly curved convex shape, which improves the reliability of the joint between the semiconductor module and the cooler. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view showing a semiconductor module according to a first embodiment. [Diagram 2] 1 is a cross-sectional view showing a semiconductor module according to a first embodiment. [Diagram 3] 2 is a bottom view showing the semiconductor module according to the first embodiment. FIG. [Figure 4] FIG. 2 is a cross-sectional view showing a modified and hardened rear metal pattern. [Diagram 5] 1 is a side view showing a power semiconductor device according to a first embodiment. [Figure 6] 4 is a flowchart showing a method for manufacturing the semiconductor module and the power semiconductor device according to the first embodiment. [Figure 7] 2A to 2C are cross-sectional views showing a method for manufacturing the semiconductor module according to the first embodiment. [Figure 8] 2A to 2C are cross-sectional views showing a method for manufacturing the semiconductor module according to the first embodiment. [Figure 9] FIG. 11 is a side view showing a semiconductor module according to a second embodiment. [Figure 10] FIG. 11 is a bottom view showing a semiconductor module according to a second embodiment. [Figure 11] FIG. 11 is a side view showing a power semiconductor device according to a second embodiment. [Figure 12] FIG. 11 is a side view showing a power semiconductor device according to a second embodiment. [Figure 13] 11 is an enlarged side view of a joint of a power semiconductor device according to a second embodiment. FIG. [Figure 14] 13 is a side view showing a modified example of the semiconductor module according to the second embodiment. FIG. [Figure 15] 13 is a bottom view showing a modified example of the semiconductor module according to the second embodiment. FIG. [Figure 16] FIG. 11 is a cross-sectional view showing a power semiconductor device according to a third embodiment. [Figure 17] FIG. 11 is a cross-sectional view showing a modified example of the power semiconductor device according to the third embodiment. [Figure 18] 11 is a flowchart showing a method for manufacturing a semiconductor module and a power semiconductor device according to a third embodiment. [Figure 19] FIG. 11 is a cross-sectional view showing a power semiconductor device according to a fourth embodiment. [Figure 20] FIG. 13 is a cross-sectional view showing a modified example of the power semiconductor device according to the fourth embodiment. [Figure 21] 13 is a flowchart showing a method for manufacturing a semiconductor module and a power semiconductor device according to a fourth embodiment. [Figure 22] FIG. 13 is a block diagram showing a configuration of a power conversion system to which a power conversion device according to a fifth embodiment is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A semiconductor module, a power semiconductor device, a method for manufacturing a semiconductor module, a method for manufacturing a power semiconductor device, and a power conversion device according to embodiments will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0011] Embodiment 1 Fig. 1 is a side view showing the semiconductor module according to embodiment 1. Fig. 2 is a cross-sectional view showing the semiconductor module according to embodiment 1. Fig. 3 is a bottom view showing the semiconductor module according to embodiment 1.

[0012] The insulating substrate 1 includes an insulating plate 1a, a front metal pattern 1b formed on the front surface of the insulating plate 1a, and a rear metal pattern 1c formed on the rear surface of the insulating plate 1a. The insulating plate 1a is made of a ceramic such as AlN (aluminum nitride), Al2O3, (alumina), or Si3N4 (silicon nitride).

[0013] The front metal pattern 1b and the back metal pattern 1c are made of conductive metal, for example, a metal mainly composed of copper or aluminum. The front metal pattern 1b and the back metal pattern 1c are joined to the insulating plate 1a by brazing. The front metal pattern 1b and the back metal pattern 1c have a thickness of 0.2 mm to 1.0 mm, and may be the same or different. The thickness of the front metal pattern 1b and the back metal pattern 1c is determined by the specifications (rated current) of the semiconductor module. The thicker these patterns are, the more they can accommodate higher currents and smaller sizes.

[0014] A semiconductor chip 2 is mounted on the surface metal pattern 1b of the insulating substrate 1. The bottom electrode of the semiconductor chip 2 is bonded to the surface metal pattern 1b of the insulating substrate 1 via a bonding material 3. The bonding material 3 is a sintered material made of fine metal powder.

[0015] The main electrode on the top surface of the semiconductor chip 2 is joined to the main terminal 4 via a bonding material 5. The other main terminal 6 is joined to the surface metal pattern 1b of the insulating substrate 1 via a bonding material 5. The bonding material 5 is solder, but may be a sintered material. The control electrode on the top surface of the semiconductor chip 2 is connected to the signal terminal 7a via a wire 8. The other surface metal pattern 1b is connected to the signal terminal 7b via a wire 8. The main terminals 4 and 6 and the signal terminals 7a and 7b are made of a conductive metal, for example, copper or a copper alloy. The wire 8 is a conductive metal mainly composed of any of aluminum, gold, silver, and copper, and is ultrasonically bonded to the control electrode and signal terminal 7a of the semiconductor chip 2, and to the surface metal pattern 1b and signal terminal 7b, respectively.

[0016] The semiconductor chip 2 is a diode, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), an IGBT (Insulated-Gate Bipolar Transistor), or an RC-IGBT (Reverse-Conducting IGBT). The semiconductor chip 2 may be a semiconductor chip having multiple functions. For example, if the semiconductor chip 2 is formed by integrating a gate balance resistor, a control circuit pattern, and a temperature sensor on a Si substrate, the layout freedom can be improved, and it is possible to reduce the size, increase the power density, and reduce the cost. In addition, the temperature of the semiconductor chip 2 can be detected, and the effective area of ​​the semiconductor chip 2 can be maximized by taking into account the heat distribution in the semiconductor module.

[0017] Sealing resin 9, which is suitable for mass production, seals (transfer molds) insulating substrate 1, semiconductor chip 2, wires 8, main terminals 4, and part of signal terminals 7. Sealing resin 9 is mainly made of epoxy resin, but is not limited to this, and any thermosetting resin having a desired elastic modulus and adhesion can be used.

[0018] The main terminals 4, 6 and the signal terminals 7a, 7b protrude from the side of the sealing resin 9. The signal terminals 7a, 7b are formed upward. The main terminals 4, 6 may be similarly formed upward. The tips of the main terminals 4, 6 and the signal terminals 7a, 7b are connected to a control board or external wiring (not shown). The back metal pattern 1c of the insulating substrate 1 is exposed at the center of the bottom surface of the sealing resin 9. The back metal pattern 1c protrudes 50 to 200 μm from the bottom surface of the sealing resin. A step 10 is provided on the outer periphery of the bottom surface of the sealing resin 9 of the semiconductor module.

[0019] The exposed surface of the rear metal pattern 1c of the insulating substrate 1 is peened, for example, by laser irradiation or projection of minute particles mainly composed of metal, resin, or ceramic. The exposed surface of the rear metal pattern 1c modified and hardened by the peening has a characteristic uneven shape according to the particle size of the particles projected in the peening. Therefore, the surface roughness Ra of the modified and hardened exposed surface of the rear metal pattern 1c is 2 to 15 μm, which is larger than the surface roughness of the front metal pattern 1b.

[0020] In addition, the exposed surface of the rear metal pattern 1c is modified and hardened, and plastically deformed, so that the rear metal pattern 1c has a downwardly warped convex shape as a whole. The height difference (warpage) between the end and center of the exposed surface of the rear metal pattern 1c is 50 to 200 μm.

[0021] 4 is a cross-sectional view showing a modified and hardened rear metal pattern. A surface layer 1ca from the lower surface of the rear metal pattern 1c to a depth of 20 to 30 μm is modified and hardened. The grain size of the metal material of the surface layer 1ca is finer than the grain size of the metal material of the interior 1cb of the rear metal pattern 1c that has not been modified and hardened.

[0022] 5 is a side view showing the power semiconductor device according to the first embodiment. In order to accommodate high current density, a cooler 12 is bonded to the exposed lower surface and side surfaces of the rear metal pattern 1c of the semiconductor module by a bonding material 11. The cooler 12 is made of an alloy mainly composed of copper or aluminum, for example. A plurality of cylindrical or rectangular prism-shaped fins 13 are formed on the lower surface of the flat plate of the cooler 12. The plurality of fins 13 may be integral with the flat plate, or may be bonded to the flat plate via a bonding material.

[0023] Solder is used as the bonding material 11. When the cooler 12 is made of aluminum or an aluminum alloy, Ni-based or Sn-based plating is applied to the upper surface of the cooler 12 to ensure solderability. Note that insulating heat dissipation grease such as Thermal Interface may be used as the bonding material 11. However, solder bonding improves the heat dissipation of the semiconductor chip 2 more than using heat dissipation grease.

[0024] Fig. 6 is a flowchart showing a method for manufacturing the semiconductor module and power semiconductor device according to embodiment 1. Fig. 7 and Fig. 8 are cross-sectional views showing the method for manufacturing the semiconductor module according to embodiment 1. Fig. 7 shows the state after wire bonding in Fig. 6, and Fig. 8 shows the state after molding in Fig. 6.

[0025] First, the insulating substrate 1 is set on a printer, and a paste-like bonding material 3 with a defined shape is applied by printing to the upper surface of the surface metal pattern 1b using a metal mask with a thickness of 100 to 200 μm. Next, the insulating substrate 1 with the bonding material 3 applied and the semiconductor chip 2 are set on a surface mounting machine, and a load is applied to mount the semiconductor chip 2 on the surface metal pattern 1b of the insulating substrate 1 (step S1). Next, these are set in a reflow furnace, the solvent is dried under a nitrogen atmosphere, and the lower electrode of the semiconductor chip 2 and the surface metal pattern 1b of the insulating substrate 1 are bonded with the bonding material 3 to each other as shown in FIG. 7.

[0026] Next, the main terminal 4 is bonded to the upper electrode of the semiconductor chip 2 by the bonding material 5 (step S2). The main terminal 6 is bonded to the surface metal pattern 1b by the bonding material 5. The bonding materials 3 and 5 may be melted and bonded at the same time. For example, the insulating substrate 1 on which the semiconductor chip 2 is mounted and the main terminal 4 are placed on a lower jig made of a material with high thermal conductivity, and are fixed and held by an upper jig made of a material with high thermal conductivity. These are placed in a device with a temperature of 200°C to 300°C and a reducing atmosphere (N2, H2), and molten solder is applied or solid solder is melted. As a result, the main terminal 4 and the semiconductor chip 2 are solder-bonded, and the main terminal 6 and the surface metal pattern 1b are solder-bonded. Thereafter, the device is moved to a cooling stage and cooled.

[0027] Next, wires 8 are ultrasonically bonded to the control electrodes of semiconductor chip 2 and signal terminals 7a to connect them, and wires 8 are ultrasonically bonded to the surface metal pattern 1b and signal terminals 7b to connect them (step S3).

[0028] Next, the thermosetting sealing resin 9 is heated, poured into a heated metal mold, and transfer molded under pressure (step S4). For example, the insulating substrate 1 and the semiconductor chip 2 are set in a metal mold heated to 150°C to 200°C, and the sealing resin 9 is poured and hardened to seal and form the outer shape. As a result, the insulating substrate 1, the semiconductor chip 2, the wires 8, parts of the main terminals 4 and 6, and parts of the signal terminals 7a and 7b are sealed with the sealing resin 9. The molded product is removed from the metal mold and placed in an oven at 150°C to 200°C for after-curing. A step 10 is formed on the outer periphery of the lower surface of the sealing resin 9 in the molded product due to the shape of the metal mold. The configuration shown in FIG. 8 is obtained by removing unnecessary terminals and resin burrs from the molded product using a metal mold.

[0029] Next, the exposed surface of the rear surface metal pattern 1c exposed from the lower surface of the sealing resin 9 and the lower surface of the sealing resin 9 are simultaneously subjected to a peening process (step S5). In the peening process, fine particles are projected onto these surfaces. By treating the entire lower surface of the rear surface metal pattern 1c at once, uniform treatment is possible. Thereafter, the pattern is washed with water and dried. The exposed surface of the rear surface metal pattern 1c that has been subjected to the peening process is modified and hardened, and the rear surface metal pattern 1c takes on a downwardly warped convex shape.

[0030] Here, before the peening treatment, the lower surface of the sealing resin 9 and the exposed surface of the back surface metal pattern 1c are flush with each other, and the back surface metal pattern 1c does not protrude from the lower surface of the sealing resin 9. The peening treatment etches the sealing resin 9 from the lower surface side, causing the back surface metal pattern 1c to protrude from the lower surface of the sealing resin 9, and the side surface of the back surface metal pattern 1c becomes exposed from the sealing resin 9. Note that in transfer molding, the bottom surface of the mold is usually made flat, so it is difficult to make the back surface metal pattern 1c protrude from the lower surface of the sealing resin 9 by transfer molding.

[0031] Next, the main terminals 4, 6 and the signal terminals 7a, 7b are plated as necessary. The plating has a material composition mainly composed of Sn or Ni. Plating improves solderability and prevents corrosion. The main terminals 4, 6 and the signal terminals 7a, 7b are bent into a shape that is easy to connect to an external terminal (step S6). Through these steps, the semiconductor module according to this embodiment is manufactured. The side and bottom surfaces of the rear metal pattern 1c of the semiconductor module are bonded to the cooler 12 with the bonding material 11 (step S7). Through the above steps, the power semiconductor device according to this embodiment is manufactured.

[0032] As described above, in this embodiment, the rear surface metal pattern 1c protrudes from the lower surface of the sealing resin 9, and the side and lower surfaces of the rear surface metal pattern 1c are exposed from the sealing resin 9. Therefore, the solder in contact with the exposed surface of the rear surface metal pattern 1c has an ideal soldering shape, improving the solderability.

[0033] In addition, the exposed surface of the rear metal pattern 1c is modified and hardened by peening treatment, and plastically deformed. As a result, the grain size of the metal material of the surface layer 1ca of the rear metal pattern 1c is finer than the grain size of the metal material of the inner part 1cb of the rear metal pattern 1c that is not modified and hardened. For example, when the rear metal pattern 1c is copper, the hardness of the modified and hardened surface layer 1ca is about 83 when measured by a Vickers hardness test, which is twice as hard as the hardness of the inner part 1cb that is not modified and hardened, which is about 48. The strength is improved by the work hardening of the surface layer 1ca of the rear metal pattern 1c. Therefore, the resistance to the shear stress generated in the solder joint due to the long-term repeated thermal stress in the usage environment of the power semiconductor device is improved, and the progress of the crack can be suppressed.

[0034] Usually, in order to reduce the contact thermal resistance, the semiconductor module is mounted on the cooler via a non-metallic heat dissipation grease such as a thermal interface material. In this case, if the back surface of the semiconductor module is concave along the upward direction, the thickness of the thermal interface material in the center becomes thick. Since the thermal conductivity of the non-metallic thermal interface material is 2 to 3 W / m·K, the thermal resistance between the semiconductor module and the cooler becomes large. In contrast, in this embodiment, the back metal pattern 1c that has been subjected to the peening process has a convex shape that is warped downward. Therefore, it can be mounted on the cooler without increasing the thermal resistance. As a result, it is possible to improve durability and fatigue strength.

[0035] In addition, the semiconductor module is composed of a plurality of members having different thermal expansion coefficients. Therefore, the operation of the semiconductor chip changes the temperature of the semiconductor module, and thermal stress occurs in each member. As a result, the entire semiconductor module is deformed so as to warp. When a conventional semiconductor module is mounted on a cooler using a thermal interface material, the warping deformation causes the thermal interface to gradually pump out and flow out to the outside. This increases the contact thermal resistance between the semiconductor module and the cooler, accelerating the deterioration of the semiconductor chip. In contrast, in this embodiment, the rear metal pattern 1c of the insulating substrate 1 is modified and hardened by a peening process, improving its strength, so that the warping deformation of the entire semiconductor module can be suppressed. This makes it possible to prevent the pumping out of the thermal interface material and suppress an increase in the contact thermal resistance between the semiconductor module and the cooler.

[0036] Therefore, according to the present embodiment, the reliability of the joint between the semiconductor module and the cooler can be improved, and as a result, a long-life, highly reliable power semiconductor device can be provided.

[0037] In addition, the exposed surface of the modified and hardened rear metal pattern 1c has an uneven surface state, and its surface roughness is greater than that of the front metal pattern 1b. Therefore, when the exposed surface of the rear metal pattern 1c is soldered to the cooler 12, the bonding strength is improved due to the anchor effect. This makes it possible to suppress the propagation of cracks.

[0038] The thickness of the front metal pattern 1b and the back metal pattern 1c are each 0.2 to 1 mm, and the thickness of the insulating plate 1a is 0.2 to 1.0 mm. With this combination of thicknesses, the bottom surface of the back metal pattern 1c is plastically deformed by the peening process so as to be extended, so that the back metal pattern 1c as a whole has a convex shape warped downward. In a conventional semiconductor module in which an insulating substrate is mounted on a base plate, it is also conceivable to perform the peening process on the base plate that is present on the entire bottom surface of the module. However, even if the base plate, which has a high original rigidity and is as thick as 3 mm to 5 mm, is subjected to the peening process, it does not reach the warpage of 50 to 200 μm required for a semiconductor module.

[0039] The insulating plate 1a of the insulating substrate 1 is made of ceramic such as AlN, which has high thermal conductivity. Therefore, heat from the semiconductor chip 2 can be dissipated to the cooler 12 via the insulating plate 1a, suppressing the temperature rise of the semiconductor chip 2. As a result, power loss can be suppressed, and the switching characteristics, lifespan, and reliability of the semiconductor module can be ensured.

[0040] The main terminals 4 and 6 protrude from the side surface of the sealing resin 9, and a step 10 is formed on the outer periphery of the lower surface of the sealing resin 9. This ensures a creepage distance between the main terminals of the semiconductor module and the upper surface of the cooler 12, and thus ensures sufficient insulation.

[0041] Embodiment 2 FIG. 9 is a side view showing a semiconductor module according to the second embodiment. FIG. 10 is a bottom view showing a semiconductor module according to the second embodiment. A first protrusion 14a and a second protrusion 14b are formed on the bottom surface of the sealing resin 9. The first protrusion 14a and the second protrusion 14b are part of the sealing resin 9, and are formed at the same time when the semiconductor chip 2 or the like is molded. The second protrusion 14b is longer than the first protrusion 14a. The first protrusion 14a is formed adjacent to the rear metal pattern 1c. Specifically, two first protrusions 14a are formed so as to sandwich the central part of the rear metal pattern 1c in the longitudinal direction. Four first protrusions 14a are formed at the four corners of the rear metal pattern 1c.

[0042] 11 and 12 are side views showing a power semiconductor device according to the second embodiment. FIG. 11 and FIG. 12 are side views seen from directions different by 90 degrees from each other. The modified and hardened rear metal pattern 1c has a convex shape warped downward. Since the rear metal pattern 1c warps in the longitudinal direction, the thickness of the bonding material 11 is small at the longitudinal center of the rear metal pattern 1c and increases toward the ends. The thickness of the bonding material 11 at the center should be at least 50 μm or more. The second protrusion 14b of the semiconductor module is brought into contact with and guided into a recess 15 formed on the upper surface of the cooler 12, and is fitted therein.

[0043] 13 is an enlarged side view of a bonding portion of the power semiconductor device according to embodiment 2. Not only the lower surface but also the side surface of the back metal pattern 1c is bonded to the bonding material 11, and the bonding material 11 forms a desired fillet. The thickness of the bonding material 11 can be ensured by the first protrusion 14a of the semiconductor module.

[0044] Next, a method for manufacturing a power semiconductor device according to the present embodiment will be described. First, a semiconductor module is manufactured by steps S1 to S6 in the same manner as in the first embodiment. Next, a solid bonding material 11 is placed at a predetermined position on the upper surface of the cooler 12. The second protrusion 14b of the semiconductor module is fitted into the recess 15 of the cooler 12 to position the semiconductor module. These are put into a reflow furnace to heat the bonding material 11, and the back metal pattern 1c of the semiconductor module and the cooler 12 are bonded by the bonding material 11. Thereafter, the power semiconductor device is cooled and taken out of the reflow furnace. Note that a sintered material may be used as the bonding material 11 instead of solder. The power semiconductor device according to the present embodiment is manufactured by the above steps.

[0045] As described above, in this embodiment, the first protrusions 14a ensure the thickness of the bonding material 11 made of heat dissipation grease or solder between the rear surface metal pattern 1c and the cooler 12. This allows the semiconductor module to be attached to the cooler 12 without increasing the thermal resistance. In addition, the progress of cracks can be suppressed, and a highly reliable and long-life power semiconductor device can be obtained.

[0046] The multiple first protrusions 14a formed on the lower surface of the sealing resin 9 allow the semiconductor module to be mounted horizontally on the upper surface of the cooler 12. This prevents the semiconductor module from tilting, and ensures a desired bonding thickness from the center to the edge of the rear metal pattern 1c.

[0047] The second protrusions 14b of the semiconductor module contact and are guided to and fitted into the recesses 15 formed on the upper surface of the cooler 12. This facilitates positioning of the semiconductor module. Although only one semiconductor module is mounted on the cooler 12 in Figs. 11 and 12, multiple semiconductor modules are usually mounted on the cooler 12 as inverter devices. By fitting the second protrusions 14b of each semiconductor module into the recesses 15 of the cooler 12, the assembly of multiple semiconductor modules becomes easier and productivity is improved. In addition, the second protrusions 14b are formed on the outer periphery of the lower surface of the sealing resin 9 relative to the first protrusions 14a so as not to interfere with the first protrusions 14a for ensuring the solder thickness.

[0048] Fig. 14 is a side view showing a modified example of the semiconductor module according to the second embodiment. Fig. 15 is a bottom view showing a modified example of the semiconductor module according to the second embodiment. A first protrusion 14a is formed on the bottom surface of the sealing resin 9, but a second protrusion 14b is not formed. The multiple first protrusions 14a formed on the bottom surface of the sealing resin 9 can ensure the thickness of the bonding material 11 between the rear surface metal pattern 1c and the cooler 12, and the semiconductor module can be mounted horizontally on the top surface of the cooler 12.

[0049] Third embodiment 16 is a cross-sectional view showing a power semiconductor device according to the third embodiment. The inside of the sealing resin 9 is not shown. A lower cooler 16 is disposed on the lower surface of the cooler 12 on which the semiconductor module is mounted. A resin case 17 is disposed on the cooler 12 so as to surround the semiconductor module. Screws 19 are fastened to the coolers 12, 16 through mounting holes 18 formed in the ends of the resin case 17. The main terminals 4 protruding from the side surfaces of the sealing resin 9 are supported by the resin case 17. The main terminals 4 and external terminals 20 overlap flatly and are soldered or laser-bonded to each other.

[0050] The coolers 12 and 16 are water-cooled and have excellent heat dissipation properties. Water-cooling liquid flows inside the lower cooler 16, and heat from the semiconductor chip 2 can be efficiently dissipated through the multiple fins 13 of the cooler 12. This significantly improves the cooling capacity, making it possible to miniaturize the semiconductor module and power semiconductor device. In addition, the heat dissipation properties of the semiconductor chip 2 are improved, so that the desired power switching can be obtained without deterioration of the characteristics, and the reliability of the power semiconductor device can be ensured. Other configurations and effects are the same as those of the first and second embodiments.

[0051] 17 is a cross-sectional view showing a modification of the power semiconductor device according to the third embodiment. The main terminal 4 and the external terminal 20 are formed facing upward and are solder-bonded or laser-bonded to each other. The other configuration is the same as that in FIG. 16.

[0052] 18 is a flowchart showing a method for manufacturing a semiconductor module and a power semiconductor device according to embodiment 3. First, a semiconductor module is manufactured by steps S1 to S6 in the same manner as in embodiment 1.

[0053] Next, a solid bonding material 11 is placed at a predetermined position on the top surface of the cooler 12. The semiconductor module is positioned by fitting the second protrusion 14b of the semiconductor module into the recess 15 of the cooler 12. These are then placed in a reflow furnace to heat the bonding material 11, thereby bonding the rear surface metal pattern 1c of the semiconductor module and the cooler 12 with the bonding material 11 (step S8). Thereafter, the power semiconductor device is cooled and removed from the reflow furnace. Note that a sintered material may be used as the bonding material 11 instead of solder.

[0054] Next, the resin case 17 is placed on the cooler 12 so as to surround the semiconductor module and support the main terminals 4 from below. The lower cooler 16 is placed on the lower surface of the cooler 12. Screws 19 are fastened to the coolers 12, 16 through mounting holes 18 formed in the resin case 17 (step S9). Note that a sealant may be inserted between the cooler 12 and the lower cooler 16, or they may be bonded together via an adhesive.

[0055] Next, the main terminal 4 and the external terminal 20 are solder-joined or laser-joined to each other (step S10). The main terminal 4 and the external terminal 20 may be laser-joined via solder. Through the above steps, the power semiconductor device according to the present embodiment is manufactured.

[0056] Fourth embodiment 19 is a cross-sectional view showing a power semiconductor device according to embodiment 4. Note that the inside of sealing resin 9 is not shown.

[0057] As in the third embodiment, the semiconductor module is bonded to the upper surface of the cooler 21 by the bonding material 11. The second protrusion 14b of the semiconductor module fits into the recess 15 formed in the upper surface of the cooler 21 to position the semiconductor module. The first protrusion 14a ensures the thickness of the bonding material 11. A resin case 17 is arranged to surround the semiconductor module and support the main terminal 4 from below. Screws 19 are fastened to the cooler 21 through mounting holes 18 formed in the resin case 17. The main terminal 4 protruding from the side of the sealing resin 9 is supported by the resin case 17. The main terminal 4 and the external terminal 20 overlap flatly and are soldered or laser bonded to each other.

[0058] The cooler 21 of this embodiment is an integrated cooler of the coolers 12 and 16 of the third embodiment. The cooler 21 is made of an alloy mainly composed of copper or aluminum, for example. The cooler 21 is of a water-cooled type and has excellent heat dissipation properties. Water-cooling liquid flows inside the cooler 21, and heat from the semiconductor chip 2 can be efficiently dissipated through the multiple fins 13 formed inside the cooler 21.

[0059] 20 is a cross-sectional view showing a modification of the power semiconductor device according to the fourth embodiment. The main terminal 4 and the external terminal 20 are formed facing upward and are solder-bonded or laser-bonded to each other. The other configuration is the same as that in FIG.

[0060] 21 is a flowchart showing a method for manufacturing a semiconductor module and a power semiconductor device according to embodiment 4. First, a semiconductor module is manufactured by steps S1 to S6 in the same manner as in embodiment 1.

[0061] Next, a solid bonding material 11 is placed at a predetermined position on the upper surface of the cooler 21. The second protrusion 14b of the semiconductor module is fitted into the recess 15 formed on the upper surface of the cooler 21 to position the semiconductor module. A resin case 17 is placed on the cooler 21 so as to surround the semiconductor module and support the main terminal 4 from below. Screws 19 are fastened to the cooler 21 through mounting holes 18 formed in the resin case 17. These are placed in a reflow furnace to heat the bonding material 11, thereby bonding the rear metal pattern 1c of the semiconductor module and the cooler 21 with the bonding material 11 (step S11). Thereafter, the power semiconductor device is cooled and removed from the reflow furnace. Note that a sintered material may be used as the bonding material 11 instead of solder.

[0062] Next, the main terminals 4, 6 and the external terminal 20 are solder-bonded or laser-bonded to each other (step S12). The main terminal 4 and the external terminal 20 may be laser-bonded via solder. Through the above steps, the power semiconductor device according to the present embodiment is manufactured.

[0063] The semiconductor chip 2 is not limited to being made of silicon, but may be made of a wide band gap semiconductor having a larger band gap than silicon. The wide band gap semiconductor is, for example, silicon carbide, gallium nitride-based material, or diamond. A semiconductor chip made of such a wide band gap semiconductor has high voltage resistance and allowable current density, and can be miniaturized. By using this miniaturized semiconductor chip, a semiconductor device incorporating this semiconductor chip can also be miniaturized and highly integrated. In addition, since the semiconductor chip has high heat resistance, the heat dissipation fins of the heat sink can be miniaturized, and the water-cooled part can be air-cooled, so the semiconductor device can be further miniaturized. In addition, since the power loss of the semiconductor chip is low and highly efficient, the efficiency of the semiconductor device can be increased.

[0064] Embodiment 5. In this embodiment, the power semiconductor devices according to the above-mentioned embodiments 1 to 4 are applied to a power conversion device. Although the present disclosure is not limited to a specific power conversion device, the following will describe a case where the present disclosure is applied to a three-phase inverter as embodiment 5.

[0065] Fig. 22 is a block diagram showing a configuration of a power conversion system to which a power conversion device according to a fifth embodiment is applied. This power conversion system includes a power supply 100, a power conversion device 200, and a load 300. The power supply 100 is a DC power supply, and supplies DC power to the power conversion device 200. The power supply 100 can be configured from various sources, for example, a DC system, a solar cell, or a storage battery, or may be configured from a rectifier circuit or an AC / DC converter connected to an AC system. The power supply 100 may also be configured from a DC / DC converter that converts DC power output from a DC system into a predetermined power.

[0066] The power conversion device 200 is a three-phase inverter connected between the power source 100 and the load 300, converts DC power supplied from the power source 100 into AC power, and supplies the AC power to the load 300. The power conversion device 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 for controlling the main conversion circuit 201 to the main conversion circuit 201.

[0067] The load 300 is a three-phase motor driven by AC power supplied from the power conversion device 200. The load 300 is not limited to a specific application, but is a motor mounted on various electric devices, and is used as, for example, a motor for a hybrid vehicle, an electric vehicle, a railroad car, an elevator, or an air conditioner.

[0068] The power conversion device 200 will be described in detail below. The main conversion circuit 201 includes switching elements and free wheel diodes (not shown), and converts DC power supplied from the power source 100 into AC power by switching the switching elements, and supplies the AC power to the load 300. There are various specific circuit configurations of 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 configured with six switching elements and six free wheel diodes connected in reverse parallel to each switching element. Each switching element and each free wheel diode of the main conversion circuit 201 is configured by a semiconductor device 202 corresponding to any one of the above-mentioned embodiments 1 to 4. Two switching elements of the six switching elements are connected in series to configure upper and lower arms, and each upper and lower arm configures 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.

[0069] The main conversion circuit 201 also includes a drive circuit (not shown) for driving each switching element, but the drive circuit may be built in the semiconductor device 202, or the semiconductor device 202 may include a drive circuit separately. The drive circuit generates drive signals for driving the switching elements of the main conversion circuit 201 and supplies them to the control electrodes of the switching elements of the main conversion circuit 201. Specifically, in accordance with a control signal from a control circuit 203 (described later), the drive signal for turning the switching element on and the drive signal for turning the switching element off are output to the control electrodes of each switching element. When maintaining the switching element in the on state, the drive signal is a voltage signal (on signal) equal to or higher than the threshold voltage of the switching element, and when maintaining the switching element in the off state, the drive signal is a voltage signal (off signal) equal to or lower than the threshold voltage of the switching element.

[0070] The control circuit 203 controls the switching elements of the main conversion circuit 201 so that a desired power is supplied to the load 300. Specifically, the control circuit 203 calculates the time (on time) for each switching element of the main conversion circuit 201 to be in the on state based on the power to be supplied to the load 300. For example, the main conversion circuit 201 can be controlled by PWM control that modulates the on time of the switching elements according to the voltage to be output. Then, a control command (control signal) is output to a drive circuit provided in the main conversion circuit 201 so that an on signal is output to a switching element that should be in the on state at each time point, and an off signal is output to a switching element that should be in the off state. The drive circuit 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.

[0071] In the power conversion device according to the present embodiment, the power semiconductor device according to any one of the first to fourth embodiments is applied as the semiconductor device 202, and therefore the reliability of the joint between the semiconductor module and the cooler can be improved.

[0072] In the present embodiment, an example of applying the present disclosure to a two-level three-phase inverter has been described, but the present disclosure is not limited thereto and can be applied to various power conversion devices. In the present embodiment, a two-level power conversion device is described, but a three-level or multi-level power conversion device may be used. In addition, when power is supplied to a single-phase load, the present disclosure may be applied to a single-phase inverter. In addition, when power is supplied to a DC load or the like, the present disclosure may be applied to a DC / DC converter or an AC / DC converter.

[0073] Furthermore, the power conversion device to which the present disclosure is applied is not limited to the case where the above-mentioned load is an electric motor, but can also be used, for example, as a power supply device for an electric discharge machine, a laser processing machine, an induction heating cooker, or a non-contact power supply system, and can also be used as a power conditioner for a solar power generation system or a power storage system, etc.

[0074] Although the preferred embodiments have been described above in detail, the present disclosure is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. Various aspects of the present disclosure are described below as appendices.

[0075] (Appendix 1) an insulating substrate having an insulating plate, a front metal pattern formed on a front surface of the insulating plate, and a rear metal pattern formed on a rear surface of the insulating plate; a semiconductor chip mounted on the surface metal pattern of the insulating substrate; a main terminal connected to a main electrode on the top surface of the semiconductor chip; a signal terminal connected by a wire to a control electrode on the top surface of the semiconductor chip; a sealing resin that seals the insulating substrate, the semiconductor chip, the wires, a portion of the main terminal, and a portion of the signal terminal, the rear metal pattern protrudes from the lower surface of the sealing resin, and the side and lower surfaces of the rear metal pattern are exposed from the sealing resin; The exposed surface of the back metal pattern is modified and hardened; The semiconductor module is characterized in that the rear metal pattern has a downwardly curved convex shape. (Appendix 2) A semiconductor module as described in Appendix 1, characterized in that the grain size of the metal material on the surface of the modified and hardened rear metal pattern is finer than the grain size of the metal material inside the rear metal pattern that has not been modified and hardened. (Appendix 3) A semiconductor module as described in Appendix 2, characterized in that the surface roughness of the exposed surface of the modified and hardened rear metal pattern is greater than the surface roughness of the front metal pattern. (Appendix 4) 4. The semiconductor module according to claim 1, wherein the thickness of the front metal pattern and the back metal pattern is 0.2 to 1 mm, and the thickness of the insulating plate is 0.2 to 1.0 mm. (Appendix 5) 5. The semiconductor module according to claim 1, wherein the insulating plate is made of ceramic. (Appendix 6) The main terminal protrudes from a side surface of the sealing resin, 6. The semiconductor module according to claim 1, wherein a step is formed on the outer periphery of the lower surface of the sealing resin. (Appendix 7) 7. The semiconductor module according to claim 1, wherein a protrusion is formed on the lower surface of the sealing resin. (Appendix 8) 8. The semiconductor module according to claim 7, wherein the protrusion has a first protrusion and a second protrusion that is longer than the first protrusion. (Appendix 9) the first protrusion is formed adjacent to the rear metal pattern; 9. The power semiconductor device according to claim 8, wherein the second protrusion is formed closer to the outer periphery of the lower surface of the sealing resin than the first protrusion. (Appendix 10) 10. The semiconductor module according to claim 1, wherein the semiconductor chip is formed of a wide band gap semiconductor. (Appendix 11) A semiconductor module according to any one of claims 1 to 10, A power semiconductor device comprising: a cooler joined to the side and bottom surfaces of the rear metal pattern of the semiconductor module by a joining material. (Appendix 12) A semiconductor module according to claim 7; a cooler bonded to the side and bottom surfaces of the rear metal pattern of the semiconductor module by a bonding material; A recess is formed on the upper surface of the cooler, The power semiconductor device according to claim 1, wherein the projection of the semiconductor module is fitted into the recess. (Appendix 13) A semiconductor module according to claim 8; a cooler bonded to the side and bottom surfaces of the rear metal pattern of the semiconductor module by a bonding material; A recess is formed on the upper surface of the cooler, The power semiconductor device, wherein the second projection is fitted into the recess. (Appendix 14) 14. The power semiconductor device according to any one of claims 11 to 13, wherein a plurality of fins are formed on a lower surface of the cooler. (Appendix 15) 15. The power semiconductor device according to any one of claims 11 to 14, wherein the cooler is of a water-cooling type. (Appendix 16) a step of mounting a semiconductor chip on a front metal pattern of an insulating substrate having an insulating plate, a front metal pattern formed on a front surface of the insulating plate, and a rear metal pattern formed on a rear surface of the insulating plate; connecting a main terminal to a main electrode on the top surface of the semiconductor chip; a step of connecting a signal terminal to a control electrode on the upper surface of the semiconductor chip by a wire; sealing the insulating substrate, the semiconductor chip, the wires, a portion of the main terminals, and a portion of the signal terminals with a sealing resin; and performing a peening process on the exposed surface of the rear surface metal pattern exposed from the lower surface of the sealing resin and the lower surface of the sealing resin by projecting particles at the same time. Before the peening process, the lower surface of the rear metal pattern and the lower surface of the sealing resin are flush with each other, After the peening process, the rear metal pattern protrudes from the lower surface of the sealing resin, and a side surface of the rear metal pattern is exposed from the sealing resin, The exposed surface of the rear metal pattern that has been subjected to the peening treatment is modified and hardened, 4. A method for manufacturing a semiconductor module, wherein the rear metal pattern subjected to peening has a downwardly curved convex shape. (Appendix 17) Manufacturing a semiconductor module by the method according to claim 16; A method for manufacturing a power semiconductor device, comprising the step of bonding a side surface and a bottom surface of the rear metal pattern of the semiconductor module to a cooler with a bonding material. (Appendix 18) 18. The method for manufacturing a power semiconductor device according to claim 17, further comprising the steps of: placing a resin case on the cooler so as to surround the semiconductor module; placing a lower cooler on an underside of the cooler; and fastening screws to the cooler and the lower cooler through mounting holes formed in the resin case. (Appendix 19) and placing a resin case on the cooler so as to surround the semiconductor module, and fastening screws to the cooler through mounting holes formed in the resin case. (Appendix 20) 20. The method for manufacturing a power semiconductor device according to any one of claims 17 to 19, further comprising forming a protrusion on a lower surface of the sealing resin, forming a recess on an upper surface of the cooler, and fitting the protrusion into the recess. (Appendix 21) A main conversion circuit having the power semiconductor device according to any one of claims 11 to 15, which converts input power and outputs the power; a control circuit that outputs a control signal for controlling the main conversion circuit to the main conversion circuit; A power conversion device comprising: [Explanation of symbols]

[0076] 1 insulating substrate, 1a insulating plate, 1b surface metal pattern, 1c back metal pattern, 1ca surface layer, 1cb inside, 2 semiconductor chip, 3,5,11 bonding material, 4,6 main terminal, 7a,7b signal terminal, 8 wire, 9 sealing resin, 10 step, 12,21 cooler, 13 multiple fins, 14a first protrusion, 14b second protrusion, 15 recess, 16 lower cooler, 17 resin case, 18 mounting hole, 19 screw, 20 external terminal, 200 power conversion device, 201 main conversion circuit, 202 semiconductor device, 203 control circuit

Claims

1. an insulating substrate having an insulating plate, a front metal pattern formed on a front surface of the insulating plate, and a rear metal pattern formed on a rear surface of the insulating plate; a semiconductor chip mounted on the surface metal pattern of the insulating substrate; a main terminal connected to a main electrode on the top surface of the semiconductor chip; a signal terminal connected by a wire to a control electrode on the top surface of the semiconductor chip; a sealing resin that seals the insulating substrate, the semiconductor chip, the wires, a portion of the main terminal, and a portion of the signal terminal, the rear metal pattern protrudes from the lower surface of the sealing resin, and the side and lower surfaces of the rear metal pattern are exposed from the sealing resin; The exposed surface of the back metal pattern is modified and hardened; The semiconductor module is characterized in that the rear metal pattern has a downwardly curved convex shape.

2. 2. The semiconductor module according to claim 1, wherein the grain size of the metal material on the surface of the modified and hardened rear metal pattern is finer than the grain size of the metal material inside the rear metal pattern that has not been modified and hardened.

3. 3. The semiconductor module according to claim 2, wherein the surface roughness of the exposed surface of the modified and hardened rear metal pattern is greater than the surface roughness of the front metal pattern.

4. 4. The semiconductor module according to claim 1, wherein the thickness of the front metal pattern and the rear metal pattern is 0.2 to 1 mm, and the thickness of the insulating plate is 0.2 to 1.0 mm.

5. 4. The semiconductor module according to claim 1, wherein the insulating plate is made of ceramic.

6. The main terminal protrudes from a side surface of the sealing resin, 4. The semiconductor module according to claim 1, wherein a step is formed on the outer periphery of the lower surface of the sealing resin.

7. 4. The semiconductor module according to claim 1, wherein a protrusion is formed on a lower surface of the sealing resin.

8. 8. The semiconductor module according to claim 7, wherein the projection comprises a first projection and a second projection that is longer than the first projection.

9. the first protrusion is formed adjacent to the rear metal pattern; 9. The semiconductor module according to claim 8, wherein the second protrusion is formed closer to the outer periphery of the lower surface of the sealing resin than the first protrusion.

10. 4. The semiconductor module according to claim 1, wherein the semiconductor chip is formed of a wide band gap semiconductor.

11. A semiconductor module according to any one of claims 1 to 3; A power semiconductor device comprising: a cooler joined to the side and bottom surfaces of the rear metal pattern of the semiconductor module by a joining material.

12. A semiconductor module according to claim 7 ; a cooler bonded to the side and bottom surfaces of the rear metal pattern of the semiconductor module by a bonding material; A recess is formed on the upper surface of the cooler, The power semiconductor device according to claim 1, wherein the projection of the semiconductor module is fitted into the recess.

13. A semiconductor module according to claim 8 ; a cooler bonded to the side and bottom surfaces of the rear metal pattern of the semiconductor module by a bonding material; A recess is formed on the upper surface of the cooler, The power semiconductor device according to claim 1, wherein the second projection is fitted into the recess.

14. 12. The power semiconductor device according to claim 11, wherein a plurality of fins are formed on a lower surface of the cooler.

15. 12. The power semiconductor device according to claim 11, wherein the cooler is of a water-cooling type.

16. a step of mounting a semiconductor chip on a front metal pattern of an insulating substrate having an insulating plate, a front metal pattern formed on a front surface of the insulating plate, and a rear metal pattern formed on a rear surface of the insulating plate; connecting a main terminal to a main electrode on the top surface of the semiconductor chip; a step of connecting a signal terminal to a control electrode on the upper surface of the semiconductor chip by a wire; sealing the insulating substrate, the semiconductor chip, the wires, a portion of the main terminals, and a portion of the signal terminals with a sealing resin; and performing a peening process on the exposed surface of the rear surface metal pattern exposed from the lower surface of the sealing resin and the lower surface of the sealing resin by projecting particles at the same time. Before the peening process, the lower surface of the rear metal pattern and the lower surface of the sealing resin are flush with each other, After the peening process, the rear metal pattern protrudes from the lower surface of the sealing resin, and a side surface of the rear metal pattern is exposed from the sealing resin, The exposed surface of the rear metal pattern that has been subjected to the peening treatment is modified and hardened, 4. A method for manufacturing a semiconductor module, wherein the rear metal pattern subjected to peening has a downwardly curved convex shape.

17. manufacturing a semiconductor module according to the method of claim 16; A method for manufacturing a power semiconductor device, comprising the step of bonding a side surface and a bottom surface of the rear metal pattern of the semiconductor module to a cooler with a bonding material.

18. 18. The method for manufacturing a power semiconductor device according to claim 17, further comprising the steps of: placing a resin case on the cooler so as to surround the semiconductor module; placing a lower cooler on an underside of the cooler; and fastening screws to the cooler and the lower cooler through mounting holes formed in the resin case.

19. 18. The method for manufacturing a power semiconductor device according to claim 17, further comprising the steps of: placing a resin case on the cooler so as to surround the semiconductor module; and fastening screws to the cooler through mounting holes formed in the resin case.

20. 20. The method for manufacturing a power semiconductor device according to claim 17, further comprising forming a protrusion on a lower surface of the sealing resin, forming a recess on an upper surface of the cooler, and fitting the protrusion into the recess.

21. a main conversion circuit having the power semiconductor device according to claim 11, which converts input power and outputs the converted power; a control circuit that outputs a control signal for controlling the main conversion circuit to the main conversion circuit; A power conversion device comprising:

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