Semiconductor device, method for manufacturing the same, and power conversion device

Abstract

The semiconductor device (1) includes a heat sink (3), an insulating layer (5), a lead frame (7), a power semiconductor element (9), a sealing resin (13), and fins (23). The heat sink (3) has a first main surface (3a) and a second main surface (3b) facing each other. A lead frame (7) including a lead terminal (7a) is disposed on the first main surface (3a) of the heat sink (3) through the insulating layer (5). The power semiconductor element (9) is mounted on the lead frame (7). The sealing resin (13) is formed to cover an inner region (4b) located inside the outer peripheral region (4a), wherein the outer peripheral region is located along the entire outer periphery of the first main surface (3a) of the heat sink (3). A first recess (15) is formed along the sealing resin (13) in the outer peripheral region (4a) at the first main surface (3a).

Description

Technical Field

[0001] This invention relates to semiconductor devices, methods for manufacturing the same, and power conversion devices. Background Technology

[0002] As a semiconductor device, there is a semiconductor device in which power semiconductor elements, which are heat-generating components, are mounted. In such a semiconductor device, heat is generated from the power semiconductor elements during operation. Therefore, in order to efficiently dissipate the generated heat, a relatively thick metal or ceramic substrate with circuit patterns is used in the semiconductor device.

[0003] In addition, to further increase the heat dissipation area and improve heat dissipation, for example, Patent Document 1 and Patent Document 2 propose semiconductor devices with heat sinks having a larger size than power modules that use resin to seal power semiconductor elements.

[0004] In the cooling structure of the power module proposed in Patent Document 1, heat transfer components such as heat transfer grease are placed between the power module, which uses resin to seal the power semiconductor element, and the heat dissipation device, which serves as a heat sink.

[0005] In the semiconductor device proposed in Patent Document 2, a semiconductor module that uses resin to seal a power semiconductor element is joined to a cooling section that serves as a heat sink by a bonding solder.

[0006] Existing technical documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2013-16606

[0008] Patent Document 2: Japanese Patent Application Publication No. 2010-114257 Summary of the Invention

[0009] In conventional semiconductor devices with heat sinks that are larger than the power module, the lead terminals connected to the lead frame protrude from the side of the resin that seals the power semiconductor element, making it difficult to seal the heat sink and the power semiconductor element together using a mold for transfer molding.

[0010] Therefore, after sealing the power semiconductor element with resin, a heat sink is mounted to the resin sealing the power semiconductor element via heat transfer components such as heat transfer grease or bonding solder. However, the thermal resistance of heat transfer components such as heat transfer grease or the thermal resistance of bonding solder becomes one of the factors that hinder further improvement of heat dissipation characteristics.

[0011] The present invention was made to solve the above-mentioned problems. One object is to provide a semiconductor device that achieves further improvement in heat dissipation characteristics, another object is to provide a method for manufacturing such a semiconductor device, and yet another object is to provide a power conversion device using such a semiconductor device.

[0012] The semiconductor device of the present invention includes a heat sink, a circuit pattern, a conductor portion, a semiconductor element, and a sealing member. The heat sink has opposing first and second main surfaces. The circuit pattern is disposed on the first main surface of the heat sink through an insulating layer. The conductor portion is electrically connected to the circuit pattern. The semiconductor element is mounted on and electrically connected to the circuit pattern. The sealing member is formed on the first main surface of the heat sink to seal the semiconductor element and the circuit pattern. The conductor portion is exposed from a surface of the sealing member located on the side opposite to the side where the heat sink is located. The sealing member is formed to cover an inner region located further inward than the outer peripheral region, wherein the outer peripheral region extends along the entire outer periphery of the first main surface of the heat sink. A first recess is formed along the sealing member in the outer peripheral region of the first main surface of the heat sink.

[0013] The semiconductor device manufacturing method of the present invention includes the following steps: Preparing a heat sink having opposing first and second main surfaces. Preparing a circuit pattern. Mounting a semiconductor element on the circuit pattern and electrically connecting the semiconductor element to the circuit pattern. For the circuit pattern, a conductor portion electrically connected to the circuit pattern is positioned on the side opposite to the side where the heat sink is positioned. On the first main surface of the heat sink, the circuit pattern with the semiconductor element electrically connected is mounted through an insulating film. Preparing a lower mold and an upper mold, wherein the upper mold has a cavity for filling a sealing member that seals the semiconductor element and the circuit pattern, and a protrusion protruding into the lower mold. Placing the heat sink with the circuit pattern mounted on the lower mold. Clamping the heat sink in the cavity using the lower and upper molds. Sealing the semiconductor element and the circuit pattern by filling the cavity with the sealing member. Removing the lower and upper molds, exposing the conductor portion from the surface of the sealing member on the side opposite to the side where the heat sink is located. In the process of clamping the radiator using the upper and lower molds, the entire outer portion of the radiator is clamped along its outer periphery. A first recess corresponding to the protrusion is formed on the first main surface of the radiator.

[0014] The power conversion apparatus of the present invention comprises: a main conversion circuit having the aforementioned semiconductor device, the main conversion circuit converting the input power and outputting it; and a control circuit that outputs a control signal for controlling the main conversion circuit to the main conversion circuit.

[0015] According to the semiconductor device of the present invention, the conductor portion is exposed from a surface of the sealing member located on the side opposite to the side where the heat sink is located. The sealing member is formed to cover an inner region located further inward than the outer peripheral region, wherein the outer peripheral region lies along the entire outer periphery of the first main surface of the heat sink. Thus, heat generated in the semiconductor element is efficiently conducted through the heat sink. As a result, the conducted heat can be dissipated efficiently, improving heat dissipation characteristics.

[0016] According to the semiconductor device manufacturing method of the present invention, in the step of clamping a heat sink using an upper mold and a lower mold, the entire outer periphery of the heat sink is clamped in, and a sealing resin is filled into the cavity. This enables the manufacture of a semiconductor device with improved heat dissipation characteristics.

[0017] According to the power conversion device of the present invention, by applying the above-described semiconductor device, a power conversion device with high heat dissipation characteristics and high insulation can be obtained. Attached Figure Description

[0018] Figure 1 This is a top view of the semiconductor device according to Embodiment 1 of the present invention.

[0019] Figure 2 This is in this implementation method Figure 1 The cross-sectional view shown at section line II-II.

[0020] Figure 3 This is a partially enlarged cross-sectional view of the semiconductor device in this embodiment.

[0021] Figure 4 This is a cross-sectional view showing one step of the manufacturing method of the semiconductor device in this embodiment.

[0022] Figure 5 This is shown in this embodiment. Figure 4 A cross-sectional view of the process following the shown process.

[0023] Figure 6 This is shown in this embodiment. Figure 5 A cross-sectional view of the process following the shown process.

[0024] Figure 7 This is shown in this embodiment. Figure 6 A cross-sectional view of the process following the shown process.

[0025] Figure 8 This is shown in this embodiment. Figure 7 A cross-sectional view of the process following the shown process.

[0026] Figure 9 This is shown in this embodiment. Figure 8 A cross-sectional view of the process following the shown process.

[0027] Figure 10 This is shown in this embodiment. Figure 9 A cross-sectional view of the process following the shown process.

[0028] Figure 11 This is shown in this embodiment. Figure 10 A cross-sectional view of the process following the shown process.

[0029] Figure 12 This is a cross-sectional view showing an example of the usage configuration of the semiconductor device in this embodiment.

[0030] Figure 13 This is a partially enlarged cross-sectional view of a semiconductor device illustrating a variation of this embodiment.

[0031] Figure 14 This is a partially enlarged cross-sectional view of the lead frame of a semiconductor device, illustrating another variation of this embodiment.

[0032] Figure 15 This is a partially enlarged cross-sectional view of the lead frame of a semiconductor device, illustrating yet another variation of this embodiment.

[0033] Figure 16 This is a cross-sectional view of the semiconductor device according to Embodiment 2 of the present invention.

[0034] Figure 17 This is a cross-sectional view showing one step of the manufacturing method of the semiconductor device in this embodiment.

[0035] Figure 18 This is shown in this embodiment. Figure 17 A cross-sectional view of the process following the shown process.

[0036] Figure 19 This is shown in this embodiment. Figure 18 A cross-sectional view of the process following the shown process.

[0037] Figure 20 This is shown in this embodiment. Figure 19 A cross-sectional view of the process following the shown process.

[0038] Figure 21 This is shown in this embodiment. Figure 20 A cross-sectional view of the process following the shown process.

[0039] Figure 22 This is shown in this embodiment. Figure 21 A cross-sectional view of the process following the shown process.

[0040] Figure 23 This is a cross-sectional view showing a step of a modified example of the manufacturing method of the semiconductor device in this embodiment.

[0041] Figure 24 This is shown in this embodiment. Figure 23 A cross-sectional view of the process following the shown process.

[0042] Figure 25 This is a cross-sectional view showing an example of a semiconductor device according to Embodiment 3 of the present invention.

[0043] Figure 26 This is a cross-sectional view showing another example of a semiconductor device in this embodiment.

[0044] Figure 27 This is a cross-sectional view showing one step of the manufacturing method of the semiconductor device in this embodiment.

[0045] Figure 28 This is a block diagram of the power conversion device according to Embodiment 4 of the present invention.

[0046] [Symbol Explanation]

[0047] 1: Semiconductor device; 3: Heat sink; 3a: First main surface; 3b: Second main surface; 4a: Outer peripheral area; 4b: Inner area; 5: Insulating layer; 7: Lead frame; 7a: Lead terminal; 8: Copper plate; 9: Power semiconductor element; 11: Bonding wire; 13: Sealing resin; 15: First recess; 17: Second recess; 19: Screw; 21: Frame; 23: Fin; 25: Metal conductor; 27: Flat fin; 29: Corrugated fin; 50: Molding mold; 51: Upper mold; 51a: Protrusion; 51b: Reception opening; 53: Lower mold; 55: Cavity; 61: Thin film; 100: Power supply; 200: Power conversion device; 201: Main conversion circuit; 202: Semiconductor module; 203: Control circuit; 300: Load. Detailed Implementation

[0048] Implementation method 1.

[0049] The semiconductor device of Embodiment 1 is described. For example... Figure 1 as well as Figure 2 As shown, the semiconductor device 1 includes a heat sink 3, an insulating layer 5, a lead frame 7, a power semiconductor element 9, a sealing resin 13, and fins 23.

[0050] The heat sink 3 has a first main surface 3a and a second main surface 3b facing each other. A lead frame 7, which is a circuit pattern, is disposed on the first main surface 3a of the heat sink 3 through an insulating layer 5. The lead frame 7 includes lead terminals 7a. A power semiconductor element 9, which is a semiconductor element, is mounted on the lead frame 7. The power semiconductor element 9 is electrically connected to the lead frame 7 by bonding wires 11.

[0051] The sealing resin 13 is a molding resin, such as an epoxy resin, used to seal the lead frame 7 and power semiconductor elements 9, forming the shape of the semiconductor device 1. The sealing resin 13 covers the first main surface 3a side of the heat sink 3. The sealing resin 13 is not formed on the second main surface 3b side of the heat sink 3.

[0052] Lead terminal 7a protrudes from the surface of the sealing resin 13 on the side opposite to the side where the heat sink 3 is located. Lead terminal 7a is connected to lead frame 7 as a conductor. Multiple fins 23 are integrally arranged on the second main surface 3b of heat sink 3.

[0053] The components constituting the semiconductor device 1 will be described in detail. By providing an insulating layer 5 on the first main surface 3a, the heat sink 3 functions as a metal plate. Furthermore, by providing fins 23 on the second main surface 3b, the heat sink 3 has sufficient heat dissipation capabilities.

[0054] The radiator 3 is formed of a metal material with high thermal conductivity and good heat dissipation, such as aluminum or copper. The fins 23 can also be flat fins or pin-shaped fins. The first recess 15 formed on the first main surface 3a of the radiator 3, as described later, is formed when the radiator 3 is clamped in the upper and lower molds in a manner that prevents the sealing resin 13 from leaking out of the mold during the heating and pressurization molding of the sealing resin 13 using a molding die.

[0055] The insulating layer 5 is formed, for example, of a thermosetting resin such as epoxy resin. To improve the heat dissipation of the insulating layer 5, the thermosetting resin is filled with a filler with high thermal conductivity. As a filler with high thermal conductivity, inorganic powders such as silica, alumina, silicon nitride, or aluminum nitride are preferred. The insulating layer 5 may be filled with an inorganic powder composed of only one of these materials, or it may be filled with an inorganic powder composed of two or more materials.

[0056] In the insulating layer 5, which has higher heat dissipation properties, inorganic powder is often highly filled into the thermosetting resin. Therefore, in order to ensure the original thermal conductivity and insulation properties, the sealing resin 13 needs to be heated and pressurized under high pressure. When the inorganic powder is filled with, for example, silicon nitride, the molding pressure for molding the sealing resin 13 is sometimes in the range of 5 MPa to 15 MPa.

[0057] The insulating layer 5 filled with such inorganic powder can be selected appropriately according to the needs. When the sealing resin 13 is heated and pressurized to harden under high molding pressure, it is necessary to increase the area of ​​the first recess 15 in a way that prevents the sealing resin from leaking out of the mold.

[0058] The lead frame 7, which serves as a circuit pattern, is formed, for example, from a stamped copper plate. The power semiconductor element 9 mounted on the lead frame 7 is not limited to a silicon-based power semiconductor element; for example, it may be a SiC-based power semiconductor element or a GaN-based power semiconductor element.

[0059] As a component for electrically connecting the lead frame 7 to the power semiconductor element 9, it is not limited to the bonding wire 11, but may also be a direct lead formed of copper plate. The lead terminal 7a at the end of the lead frame 7 is not exposed from the side of the sealing resin 13, but is exposed and protruding from the surface of the sealing resin 13 on the side opposite to the side where the heat sink 3 is located, as described above.

[0060] The sealing resin 13 is formed to cover an inner region 4b located inside the outer peripheral region 4a, wherein the outer peripheral region 4a is the portion covering the entire outer periphery along the outer periphery of the first main surface 3a of the heat sink 3. A first recess 15 is formed along the sealing resin 13 in the outer peripheral region 4a not covered by the first main surface 3a. Burrs of the sealing resin 13 may also be attached to the surface of the portion of the outer peripheral region 4a of the heat sink 3 where the first recess 15 is not formed.

[0061] Moreover, the preferred option is as follows: Figures 1-3 As shown, a second recess 17 is formed in the inner region 4b of the first main surface 3a of the heat sink 3, which is covered by sealing resin 13. During the transfer molding process, the second recess 17 is filled with sealing resin 13, thereby improving the adhesion between the sealing resin 13 and the heat sink 3, or its crack resistance. For example, during reliability tests that alternate between high-temperature and low-temperature tests (temperature cycling), the sealing resin 13 is prevented from detaching from the heat sink 3 or from cracking within the sealing resin 13.

[0062] The shape (cross-sectional shape) of the second recess 17 can be semi-circular or rectangular, but it is preferably a shape in which the sealing resin 13 filling the second recess 17 is not easily detached from the second recess 17. The method of forming the second recess 17 is not limited to machining, and it can also be formed by forging or multi-layer stamping. The method of forming the second recess 17 can be appropriately selected considering reliability or production cost.

[0063] Furthermore, the sealing resin 13 preferably contains inorganic powders such as silicon dioxide or aluminum oxide. In a sealing resin 13 containing such inorganic powders, the coefficient of thermal expansion of the sealing resin 13 can be made close to that of the heat sink 3, the lead frame, and the power semiconductor element 9, thereby suppressing overall warping of the semiconductor device 1. The semiconductor device 1 of Embodiment 1 is configured as described above.

[0064] Next, an example of the manufacturing method of the aforementioned semiconductor device will be described. For example... Figure 4 As shown, a heat sink 3 having opposing first main surfaces 3a and second main surfaces 3b is prepared. Multiple fins 23 are provided on the second main surface 3b of the heat sink 3. Additionally, a second recess 17 is formed on the first main surface 3a of the heat sink 3.

[0065] Next, a lead frame 7 is mounted on the first main surface 3a of the heat sink 3 (see reference). Figure 2 The area of ​​the heat sink 3 is coated with a highly thermally conductive resin composition (material) made of epoxy resin to form an insulating layer 5. In addition to coating with a resin composition, a sheet-like resin composition may be pressurized to adhere tightly to the first main surface 3a of the heat sink 3.

[0066] Next, prepare the lead frame by applying solder paste to the areas where power semiconductor components and other electronic parts will be mounted. Next, place the electronic parts on top of the solder paste. Then, as... Figure 5 As shown, for example, electronic components such as power semiconductor elements 9 are mounted onto lead frames 7 via a reflow process.

[0067] Next, as Figure 6 As shown, the power semiconductor element 9, etc., is electrically connected to the lead frame 7 using bonding wire 11. Besides bonding wire, direct wiring, such as using a copper plate, can also be used. Next, in the lead frame 7, the portion that will become the lead terminal 7a is bent upwards (see reference). Figure 7 Alternatively, electronic components can be mounted on the lead frame 7 after the portion of the lead frame 7 that becomes the lead terminal 7a has been bent beforehand.

[0068] Next, as Figure 7 As shown, a lead frame 7, on which power semiconductor components 9 are mounted, is placed on the insulating layer 5. Next, as... Figure 8 As shown, an upper mold 51 and a lower mold 53 are prepared as the molding die 50 for transfer molding. In the upper mold 51, a protrusion 51a protruding toward the lower mold 53 is formed to suppress leakage of the sealing resin filling the cavity. In addition, a receiving opening 51b for receiving lead terminals is formed in the upper mold 51.

[0069] Next, as Figure 9 As shown, the heat sink 3, equipped with the lead frame 7, is placed in the lower mold 53. Next, as... Figure 10 As shown, the upper mold 51 is brought close to the lower mold 53, and the outer peripheral portion of the heat sink 3 is clamped in using the upper mold 51 and the lower mold 53. In the first main surface 3a, the area where the upper mold 51 abuts is the outer peripheral area 4a (see reference). Figure 1 ).

[0070] At this time, the lead terminal 7a is inserted into the receiving opening 51b of the upper mold 51. Here, the upper mold 51 may also have a mechanism capable of changing the width of the receiving opening 51b. Therefore, when the heat sink 3 is clamped in using the upper mold 51 and the lower mold 53, the opening width of the receiving opening 51b is set to be sufficiently wider than the thickness of the lead terminal 7a, thereby allowing the lead terminal 7a to be easily inserted into the receiving opening 51b. After the lead terminal 7a is inserted into the receiving opening 51b, the opening width of the receiving opening 51b can be set to match the thickness of the lead terminal 7a, allowing the sealing resin 13 (refer to...) to... Figure 11 ) inflow.

[0071] The mating surfaces of the upper mold 51 and the lower mold 53 are approximately aligned with the surface where the first main surface 3a of the heat sink 3 is located. Here, the pressure for clamping the heat sink 3 is adjusted such that the protrusion 51a formed on the upper mold 51 is inserted into the first main surface 3a of the heat sink 3.

[0072] Next, as Figure 11 As shown, the sealing resin 13 flows into the cavity 55. At this time, the protrusion 51a of the upper mold 51 is inserted into the first main surface 3a of the radiator 3, thereby suppressing the leakage of the sealing resin 13 from the cavity 55 to the mating surface of the first main surface 3a of the radiator 3 and the upper mold 51.

[0073] The sealing resin 13 is heated and hardened within the molding die 50 (cavity 55). After the sealing resin 13 has hardened, the semiconductor device 1 is removed from the molding die 50. Subsequently, additional heat curing treatment can be performed using an oven or the like, as needed, to make the sealing resin 13 even more effective.

[0074] like Figure 12As shown, in the semiconductor device 1 that undergoes heat curing, the semiconductor device 1 is mounted on the frame 21, thereby enabling the use of an air-cooled or water-cooled structure. One method for mounting the semiconductor device 1 on the frame 21 is, for example, to fix the heat sink 3 to the frame 21 using screws 19. Alternatively, the heat sink 3 can also be fixed to the frame 21 by welding or friction stir welding.

[0075] In the aforementioned semiconductor device 1, the sealing resin 13, which seals the power semiconductor element 9, is directly formed on the first main surface 3a of the heat sink 3, and the sealing resin 13 is integrated with the heat sink 3. Furthermore, the sealing resin 13 is formed to cover an inner region 4b located inside the outer peripheral region 4a, wherein the outer peripheral region 4a extends along the entire outer periphery of the first main surface 3a of the heat sink 3, and its area when viewed from above is larger than the area when viewed from above the sealing resin 13.

[0076] As a result, the thermal resistance is reduced by a corresponding amount, eliminating the need for applying heat-transfer grease or similar materials, allowing heat generated in the power semiconductor element 9 to be conducted to the heat sink 3 more efficiently. Consequently, the conducted heat can be dissipated more efficiently, improving heat dissipation characteristics.

[0077] In addition, the sealing resin 13 and the heat sink 3 are integrated, so that after the sealing resin 13 for sealing power semiconductor components is molded, the heat sink 3 does not need to be installed, which helps to reduce manufacturing steps.

[0078] Furthermore, the lead terminal 7a does not protrude from the side of the sealing resin 13, but rather from the upper surface of the sealing resin 13. The lead terminal 7a protrudes from the surface of the sealing resin 13 on the side opposite to the side where the heat sink 3 is located. This facilitates the miniaturization of the semiconductor device 1.

[0079] Furthermore, when the sealing resin 13 is integrally formed on the heat sink 3, the upper mold 51 and the lower mold 53 are used to clamp the outer peripheral portion of the heat sink 3 according to the shape that the matching surface of the upper mold 51 and the lower mold 53 is approximately consistent with the surface where the first main surface 3a of the heat sink 3 is located, and the protrusion 51a of the upper mold 51 will sink into the first main surface 3a of the heat sink 3.

[0080] This prevents leakage of the sealing resin 13 filled in the cavity 55 to the mating surface of the first main surface 3a of the radiator 3 and the upper mold 51. The protrusion 51a of the upper mold 51 is recessed into the first main surface 3a of the radiator 3, thereby forming the first recess 15 along the sealing resin 13 on the first main surface 3a.

[0081] Furthermore, when the sealing resin 13 is integrally formed on the heat sink 3, a portion of the sealing resin 13 filled in the cavity 55 is also filled into the second recess 17 formed on the first main surface 3a of the heat sink 3. This improves the adhesion between the sealing resin 13 and the heat sink 3.

[0082] Furthermore, regarding the aforementioned semiconductor device 1, a second recess 17 is described where a first main surface 3a of the heat sink 3 is formed. Alternatively, as... Figure 13 As shown, the heat sink 3 is applied to the first main surface 3a where the second recess is not formed.

[0083] Furthermore, regarding the aforementioned semiconductor device 1, a structure has been described in which the lead frame 7 is bent once until it is exposed from the surface of the sealing resin 13. As for the structure of the lead frame 7, for example, the structure can be appropriately modified considering factors such as the insulation distance between the lead frame 7 and the heat sink 3, or the connection with the direct lead. Alternatively, as... Figure 14 As shown, for example, the lead frame 7 is bent into a multi-level structure. Alternatively, it can be as follows... Figure 15 As shown, this is a semi-stamping structure with an offset of approximately half the thickness of the lead frame 7.

[0084] Implementation method 2.

[0085] The semiconductor device of Embodiment 2 is described. For example... Figure 16 As shown, in the semiconductor device 1, a circuit pattern, such as the pattern of a copper plate 8, is disposed on the first main surface 3a of the heat sink 3 through an insulating layer 5. A metal conductor 25 is electrically connected to the copper plate 8 as a conductor portion.

[0086] The metal conductor 25 is exposed on the surface of the sealing resin 13 on the side opposite to where the heat sink 3 is located. Furthermore, regarding other structures, ... Figure 1 as well as Figure 2 Since the semiconductor device 1 shown has the same structure, the same symbols are added to the same components, and the description is not repeated except where necessary.

[0087] Next, an example of the manufacturing method of the aforementioned semiconductor device will be described. For example... Figure 17 As shown, a copper plate 8 is placed on the first main surface 3a of the heat sink 3 through an insulating layer 5, and then stamped (heated and pressurized) to harden the insulating layer 5. Next, the copper plate 8 is etched to form a circuit pattern on the copper plate 8. Next, as... Figure 18 As shown, the power semiconductor element 9 and the metal conductor 25 are respectively soldered to the copper plate 8. Next, as... Figure 19 As shown, the power semiconductor element 9 and the copper plate 8 are electrically connected by bonding wire 11.

[0088] Next, as Figure 20 As shown, the heat sink 3, which includes the copper plate 8, is placed in the lower mold 53. Next, as... Figure 21 As shown, the upper mold 51 is brought close to the lower mold 53, and the outer peripheral portion of the heat sink 3 is clamped in using the upper mold 51 and the lower mold 53. Here, the pressure of clamping the heat sink 3 is adjusted so that the protrusion 51a formed on the upper mold 51 is inserted into the first main surface 3a of the heat sink 3.

[0089] Next, as Figure 22 As shown, sealing resin 13 flows into cavity 55. The sealing resin 13 is heated and hardened within the molding die 50 (cavity 55). After the sealing resin 13 has hardened, the semiconductor device 1 is removed from the molding die 50, completing the process. Figure 16 Semiconductor device 1 is shown.

[0090] In the semiconductor device 1 described above, similarly to the semiconductor device 1 described earlier, the sealing resin 13 and the heat sink 3 are integrated, and the area of ​​the heat sink 3 when viewed from above is larger than the area of ​​the sealing resin 13 when viewed from above. This allows heat generated in the power semiconductor element 9, etc., to be efficiently conducted through the heat sink 3. As a result, the conducted heat can be dissipated efficiently, improving heat dissipation characteristics.

[0091] Furthermore, similar to the semiconductor device 1 described above, after the sealing resin 13 that seals the power semiconductor element 9 is molded, there is no need to install the heat sink 3, which helps to reduce manufacturing steps. Moreover, the metal conductor 25 does not protrude from the side of the sealing resin 13, but rather protrudes upward from the top surface. This contributes to the miniaturization of the semiconductor device 1.

[0092] However, in the above-described semiconductor device manufacturing method, compared with the semiconductor device manufacturing method described above, it is conceivable that due to the deviation of the finishing dimensions when welding the metal conductor 25 to the copper plate 8 or the dimensional tolerance of the metal conductor 25, the height of the metal conductor 25 from the heat sink 3 will be deviated.

[0093] Therefore, in order to fill the cavity 55 with sealing resin 13 while the heat sink 3 is reliably clamped in the upper mold 51 and the lower mold 53, it is preferable to use a heat-resistant film capable of absorbing the tolerance (deviation) of the height of the metal conductor 25 from the heat sink 3. This process will be explained.

[0094] like Figure 23 As shown, a heat-resistant film 61 is disposed between the lower mold 53, which is equipped with a heat sink 3, and the upper mold 51. Next, the heat-resistant film 61 is moved along the surface of the cavity 55 by means of vacuum adsorption, for example, and the heat sink 3 is clamped in by the upper mold 51 and the lower mold 53 (see reference). Figure 24 Next, as Figure 24 As shown, sealing resin 13 is filled into cavity 55. After the sealing resin 13 is heated and hardened, semiconductor device 1 is removed from molding die 50.

[0095] In the manufacturing method using a heat-resistant film, the heat-resistant film 61 disposed between the metal conductor 25 and the upper mold 51 acts as a buffer. Therefore, when the height of the metal conductor 25 from the heat sink 3 is greater than the reference height, when the heat sink 3 is clamped between the upper mold 51 and the lower mold 53, the metal conductor 25 sinks into the heat-resistant film 61, thereby mitigating the pressure exerted on the metal conductor 25 from the upper mold 51. As a result, damage to the joint between the metal conductor 25 and the copper plate 8 can be suppressed, and damage to the insulating layer 5 located beneath the copper plate 8 can also be suppressed.

[0096] In the semiconductor device 1 manufactured in this way, the upper part of the metal conductor 25 protrudes slightly from the surface of the sealing resin 13. Furthermore, after manufacturing the semiconductor device 1, the heat-resistant film 61 remaining on the upper mold 51 is recycled and discarded.

[0097] Implementation method 3.

[0098] Regarding the semiconductor device 1 described above, the case where multiple fins 23 are integrally disposed on the second main surface 3b of the heat sink 3 is explained. Here, the heat sink and the multiple fins are described as separate entities in the semiconductor device.

[0099] like Figure 25 As shown, for example, the flat fin 27 is bonded to one side of the second main surface 3b of the heat sink 3 in the semiconductor device 1. Additionally, as... Figure 26 As shown, for example, corrugated fins 29 are attached to one side of the second main surface 3b of the heat sink 3 in the semiconductor device 1.

[0100] As such flat fins 27 or corrugated fins 29, relatively inexpensive fins manufactured by aluminum extrusion can also be used. Alternatively, a flexible fin structure can be constructed by bending a thin sheet of aluminum into a fin shape. Fins that are separate from the heat sink 3 can be joined to the heat sink 3 by solder-based joining, laser welding, or riveting.

[0101] In semiconductor devices where the heat sink and multiple fins are separate entities, the molding pressure of the sealing resin can be increased during the transfer molding process. Explain this situation. For example... Figure 27 As shown, the radiator 3 and the multiple fins are set as different bodies, so that they can contact the entire surface of the second main surface 3b of the radiator 3 in the lower mold 53 on which the radiator 3 is placed.

[0102] Therefore, the molding pressure during molding by filling the cavity 55 with sealing resin 13 can reliably prevent the radiator from deforming. As a result, compared to using a lower mold 53 (refer to) that houses a radiator 3 with multiple fins 23, this method effectively prevents deformation of the radiator. Figure 10 Compared to situations like (etc.), it is possible to set higher molding pressure.

[0103] To ensure the original thermal conductivity and insulation properties of the insulating layer 5 between the heat sink 3 and the lead frame 7, the more inorganic powder is used, the higher the pressure curing required during the heat curing of the epoxy resin or other resin that forms the base of the insulating layer 5. In particular, the shape of the inorganic powder has a significant impact on pressure curing. When silicon nitride is used to fill the insulating layer 5, compared to when silicon dioxide or alumina is used, the non-spherical shape of silicon nitride results in lower fluidity of the insulating layer 5, often requiring higher pressure to maintain its original thermal conductivity and other properties.

[0104] When the insulating layer 5 is heated and pressurized in the cavity of a mold used for transfer molding to harden it, it can be used as a heat sink and multiple fins can be used to form a heat sink of different bodies, thereby enabling hardening under higher pressure, and ensuring higher thermal conductivity as the insulating layer 5.

[0105] When silicon nitride is used as an inorganic powder, if the volume ratio of silicon nitride to the volume of the insulating layer filled with silicon nitride (the volume ratio of silicon nitride) is less than 40% of the volume, the molding pressure during heat curing is about 5 MPa, which can ensure the original thermal conductivity and insulation properties. The thermal conductivity is about 2 to 5 W / (m·K). When the volume ratio of silicon nitride is more than 40% but less than 50% of the volume, a molding pressure of about 10 MPa is required, and the thermal conductivity is about 4 to 6 W / (m·K).

[0106] When the volume fraction of silicon nitride is 50% or more but less than 60% by volume, the thermal conductivity can reach 5–14 W / (m·K). In this case, a molding pressure of 10 MPa or higher is required. Therefore, if… Figure 27 As shown, a lower mold 53 is applied to the entire surface of the second main surface 3b of the heat sink 3, thereby enabling the manufacture of a more reliable semiconductor device with excellent insulation and thermal conductivity.

[0107] Implementation method 4.

[0108] Here, a power conversion device applied to the semiconductor device described in Embodiments 1 to 3 above will be explained. The present invention is not limited to a specific power conversion device; Embodiment 4 will be used to describe the application of the present invention to a three-phase inverter.

[0109] Figure 28 This is a block diagram showing the structure of the power conversion system of the power conversion device applied in this embodiment. Figure 28 The power conversion system shown includes a power source 100, a power conversion device 200, and a load 300. The power source 100 is a DC power source that supplies DC power to the power conversion device 200. The power source 100 can be of various types, such as a DC system, a solar cell, or a battery. Alternatively, it can be constructed from a rectifier circuit or an AC / DC converter connected to an AC system. Alternatively, the power source 100 can be constructed from a DC / DC converter that converts DC power output from a DC system into a predetermined power.

[0110] The power conversion device 200 is a three-phase inverter connected between the power source 100 and the load 300, which converts the DC power supplied from the power source 100 into AC power to supply AC power to the load 300. Figure 28 As shown, 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 to the main conversion circuit 201.

[0111] Load 300 is a three-phase motor driven by AC power supplied from power conversion device 200. Furthermore, load 300 is not limited to a specific application; it is a motor mounted on various electrical equipment, such as those used in hybrid vehicles, electric vehicles, railway vehicles, elevators, or air conditioning systems.

[0112] The following describes the detailed contents of the power conversion device 200. The main conversion circuit 201 includes switching elements and freewheeling diodes (neither shown). The switching elements switch, thereby converting the DC power supplied from the power source 100 into AC power and supplying it to the load 300. The specific circuit structure of the main conversion circuit 201 varies; in this embodiment, the main conversion circuit 201 is a two-level three-phase full-bridge circuit, which can be constructed from six switching elements and six freewheeling diodes connected in anti-parallel to each switching element.

[0113] In at least one of the switching elements and freewheeling diodes of the main converter circuit 201, the semiconductor device 1 of at least one of the embodiments 1 to 3 described above is configured as a semiconductor module 202. Regarding the six switching elements, upper and lower branches are formed by connecting two switching elements in series at a time, and each upper and lower branch constitutes a phase (U phase, V phase, W phase) of the full-bridge circuit. Furthermore, the output terminals of each upper and lower branch, i.e., the three output terminals of the main converter circuit 201, are connected to the load 300.

[0114] Additionally, the main converter circuit 201 includes a drive circuit (not shown) for driving each switching element. However, the drive circuit can be either integrated into the semiconductor module 202 or have a separate structure from the semiconductor module 202. The drive circuit generates drive signals to drive the switching elements of the main converter circuit 201 and supplies them to the control electrodes of the switching elements. Specifically, according to the control signal from the control circuit 203 (described later), drive signals that turn the switching elements on and off are output to the control electrodes of each switching element. When the switching element is held in the on state, the drive signal is a voltage signal above the threshold voltage of the switching element (on signal); when the switching element is held in the off state, the drive signal is a voltage signal below the threshold voltage of the switching element (off signal).

[0115] The control circuit 203 controls the switching elements of the main converter circuit 201 to supply the desired power to the load 300. Specifically, based on the power to be supplied to the load 300, the control circuit 203 calculates the time (on-time) during which each switching element of the main converter circuit 201 should be in the on state. For example, the main converter circuit 201 can be controlled by PWM control that modulates the on-time of the switching elements according to the output voltage. Then, the control circuit outputs control commands (control signals) to the drive circuit of the main converter circuit 201 in such a way that it outputs on-signals to the switching elements that should be in the on state and off-signals to the switching elements that should be in the off state at each time point. The drive circuit outputs the on-signal or off-signal as drive signals to the control electrodes of each switching element according to the control signals.

[0116] In the power conversion device of this embodiment, the semiconductor device 1 of the above embodiments 1 to 3 is used as a semiconductor module 202 in at least one of the switching elements and freewheeling diodes of the main conversion circuit 201, so the electrical insulation can be improved and the reliability of the power conversion device can be improved.

[0117] In this embodiment, an example of applying the present invention to a 2-level three-phase inverter is described, but the present invention is not limited thereto and can be applied to various power conversion devices. Although this embodiment describes a 2-level power conversion device, it could also be a 3-level or multi-level power conversion device. When supplying power to a single-phase load, the present invention can also be applied to a single-phase inverter. Furthermore, when supplying power to DC loads, the present invention can also be applied to DC / DC converters or AC / DC converters.

[0118] Furthermore, the power conversion device of the present invention is not limited to the case where the load is an electric motor. For example, it can also be used as a power supply device for electrical discharge machining, laser processing machine, induction heating cooker or non-contact power supply system, and can also be used as a power regulator for solar power generation system or energy storage system.

[0119] Furthermore, the semiconductor devices described in each embodiment can be combined in various ways as needed. Additionally, dependent claims described in the claims are also pre-determined to correspond to their respective combinations.

[0120] The embodiments disclosed herein are merely illustrative and are not intended to be limiting. The invention is not shown within the scope of the foregoing description, but rather through the claims, and is intended to include all modifications of the same meaning and scope as the claims.

[0121] Industrial availability

[0122] The present invention is effectively used in semiconductor devices equipped with power semiconductor elements and power conversion devices using such semiconductor devices.

Claims

1. A method for manufacturing a semiconductor device, comprising: A process for preparing a heat sink having an opposing first main surface and a second main surface and being formed of any material, such as copper or aluminum; The process of preparing circuit patterns; The process of mounting a semiconductor element on the circuit pattern and electrically connecting the semiconductor element to the circuit pattern; The process of configuring a conductor portion electrically connected to the circuit pattern on the side opposite to the side where the heat sink is configured; The process of mounting the circuit pattern of the semiconductor element electrically connected to the first main surface of the heat sink, separated by an insulating film; The process of preparing a lower mold and an upper mold, wherein the upper mold has a cavity for filling a sealing member that seals the semiconductor element and the circuit pattern, and a protrusion that protrudes into the lower mold; The process of placing the heat sink with the circuit pattern onto the lower mold; The process of clamping the heat sink using the lower mold and the upper mold in a form that houses the semiconductor element and the circuit pattern within the cavity; The process of sealing the semiconductor element and the circuit pattern by filling the cavity with a sealing member; and The process of disassembling the lower mold and the upper mold to expose the conductor portion from the surface of the sealing member located on the side opposite to the side where the heat sink is located. In the process of clamping the heat sink using the upper mold and the lower mold The entire outer periphery of the radiator is clamped in. In a portion of the first main surface of the heat sink, a first recess corresponding to the protrusion is formed by recessing the protrusion into the first main surface of the heat sink, in a configuration that is located on the outer side of the sealing member that seals the circuit pattern disposed on the first main surface of the heat sink and the semiconductor element mounted on the circuit pattern, with the protrusion recessed into the first main surface of the heat sink.

2. The method for manufacturing a semiconductor device according to claim 1, wherein, have: The process of setting heat dissipation fins on one side of the second main surface of the radiator after disassembling the lower mold and the upper mold.

3. The method for manufacturing a semiconductor device according to claim 2, wherein, In the process of preparing the lower mold, a lower mold is prepared that has a mounting portion that contacts the entire surface of the second main surface of the heat sink.

4. The method for manufacturing a semiconductor device according to claim 1, wherein, In the process of preparing the circuit pattern, a lead frame including portions that become lead terminals is prepared. In the process of configuring the conductor portion, the portion that becomes the lead terminal is configured as the conductor portion.

5. The method for manufacturing a semiconductor device according to claim 1, wherein, In the process of preparing the circuit pattern, the metal plate is patterned. In the process of assembling the conductor portion, a metal conductor is joined to the metal plate as the conductor portion.

6. The method for manufacturing a semiconductor device according to claim 5, wherein, In the process of sealing the semiconductor element and the circuit pattern, the sealing member is filled into the cavity while a heat-resistant film is placed between the upper mold and the metal conductor.

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