Semiconductor module

Abstract

Semiconductor module, comprising: - a frame part (1, 2); - a semiconductor device (5, 6) mounted on an upper surface of the frame part (1); - a heat sink (12) connected to a lower surface of the frame part (1); - an insulating film (13) arranged on a lower surface of the heat sink (12); and - a sealing component (14) that seals the frame part (1, 2), the semiconductor device (5, 6) and the heat sink (12) to form a module body (15), wherein: - a thickness (A) of the heat sink (12) is equal to or greater than 50% of a thickness (B) of the module body (15) and - the heat sink (12) has a trapezoidal cross-section, in which a lower side closer to the insulating film (13) is longer than an upper side closer to the frame part (1).

Description

Background of the invention: Area

[0001] The present invention relates to a semiconductor module. background

[0002] A transfer-molding power module utilizing a high-heat-dissipation insulating film made of a resin composite material is used in a variety of applications, including household appliances. The semiconductor device is mounted on the top surface of a frame, and a heat sink is positioned on the bottom surface of the frame to further enhance heat dissipation. The insulating film is designed to isolate the power circuitry within the module from the external environment.

[0003] Traditionally, the insulating film was positioned between the frame and the heat sink. The insulating film is adjacent to the semiconductor device, which acts as a heat source, and therefore the insulating film must exhibit high thermal resistance. In another disclosed configuration, the insulating film is arranged on the lower surface of the heat sink (see, for example, Japanese patent application JP 2016-092 184 A); however, the temperature rise of the insulating film could not be sufficiently reduced with this configuration alone.

[0004] DE 102 21 891 A1 describes a semiconductor device that meets the requirements for both radiation efficiency and miniaturization, and which simultaneously incorporates a high-current semiconductor element. The semiconductor device comprises an IGBT element and a diode element mounted on the main surface of a strip-shaped heat spreader made of a metal with excellent thermal and electrical conductivity. A relay terminal block is also provided externally to the IGBT element on the main surface of the heat spreader, with the relay terminal block, the IGBT element, and the diode element aligned with one another. Furthermore, external terminal electrode plates are provided on both sides of this aligned arrangement.The heat distributor, the IGBT element, the diode element, the relay terminal block and the outer terminal electrode plate are molded into a box-shaped resin material by injection molding, the resin housing defining the outer shape of the semiconductor device. Summary

[0005] To obtain an insulating film with high heat resistance, it is necessary to adjust the proportion or content of a filler or to change the resin material. Such a change makes the insulating film more expensive and thus increases manufacturing costs, which posed a problem.

[0006] The present disclosure is intended to solve the problem described above and to obtain a semiconductor module for which manufacturing costs can be reduced.

[0007] The problem underlying the invention is solved according to the invention in a semiconductor module by the features of claim 1. Advantageous further developments are the subject of the respective dependent claims.

[0008] A semiconductor module according to the present invention comprises: a frame; a semiconductor device mounted on an upper surface of the frame; a heat sink connected to a lower surface of the frame; an insulating film arranged on a lower surface of the heat sink; and a sealing element that seals the frame, the semiconductor device, and the heat sink to form a module body, wherein the thickness of the heat sink is equal to or greater than 50% of the thickness of the module body. According to the invention, the heat sink has a trapezoidal cross-section, wherein a lower side closer to the insulating film is longer than an upper side closer to the frame.

[0009] A method for manufacturing a semiconductor module, described in the technical background of the present invention, may, for example, comprise: arranging an insulating film on a lower surface of a heat sink; placing the heat sink and the insulating film in a first mold and sealing the heat sink and the insulating film with a first sealing component to form a lower part of the module; placing a frame part on an upper surface of the heat sink, which is exposed without the first sealing component; mounting the semiconductor device on an upper surface of the frame part; and placing the lower part of the module, the frame part, and the semiconductor device in a second mold and sealing the frame part and the semiconductor device with a second sealing component to form an upper part of the module.

[0010] In the semiconductor module according to the present invention, an insulating film is arranged on a lower surface of the heat sink, and the thickness of the heat sink is equal to or greater than 50% of the thickness of the module body. The insulating film is sufficiently separated from the semiconductor device as a heat source, thus preventing thermal failure of the insulating film. Therefore, a highly heat-resistant insulating film is not required, and manufacturing costs can be reduced.

[0011] In the method for manufacturing the semiconductor module described in the further technical background of the present invention, the lower part of the module and the upper part of the module are subjected to separate shaping processes. Accordingly, the resin material and the shaping conditions can be individually selected for each of the sealing components. As a result, the manufacturing process can be simplified and manufacturing costs reduced.

[0012] Other and further aims, features and advantages of the invention will become more fully apparent from the following description. Brief description of the drawings Fig. Figure 1 is a cross-sectional view illustrating a semiconductor module according to one embodiment to explain the technical background of the present invention. Fig. Figure 2 is a cross-sectional view illustrating a semiconductor module according to a comparative example. Fig. Figure 3 is a diagram illustrating the relationship between the ratio of the thickness of the heat sink relative to the thickness of the module body and the temperature of the insulating film. Fig. Figure 4 is a cross-sectional view illustrating a semiconductor module according to an embodiment of the present invention. Fig. Figure 5 is a cross-sectional view illustrating a method for manufacturing the semiconductor module according to the embodiment, in order to explain the technical background of the present invention. Fig. Figure 6 is a cross-sectional view illustrating a method for manufacturing the semiconductor module according to the embodiment, in order to explain the technical background of the present invention. Fig. Figure 7 is a cross-sectional view illustrating a method for manufacturing the semiconductor module according to the embodiment, in order to explain the technical background of the present invention. Fig. Figure 8 is a cross-sectional view illustrating a method for manufacturing the semiconductor module according to the embodiment, in order to explain the technical background of the present invention. Fig. Figure 9 is a cross-sectional view illustrating a method for manufacturing the semiconductor module according to the embodiment, in order to explain the technical background of the present invention. Description of the embodiments

[0013] A semiconductor module of the present invention and – to explain the technical background of the present invention – a method for its fabrication are described with reference to the drawings. The same components are designated by the same symbols, and their repeated description can be omitted. Exemplary embodiment and technical background of the present invention

[0014] Fig. Figure 1 is a cross-sectional view illustrating a semiconductor module according to one embodiment to explain the technical background of the present invention. Frame parts 1 and 2 and terminals 3 and 4 are arranged at the same level and separated from each other. Semiconductor devices 5 and 6 are mounted on the upper surface of frame part 1. For example, semiconductor device 5 is an IGBT and semiconductor device 6 is a diode. A control element 7 is mounted on frame part 2. Electrodes on the upper surface of semiconductor devices 5 and 6 are connected to each other by a wire 8. The electrode on the upper surface of semiconductor device 6 is connected to one end of terminal 3 by a wire 9. A control electrode of semiconductor device 5 is connected to the control element 7 by a wire 10.The control element 7 and one end of the terminal 4 are connected to each other by a wire 11. The control element 7 controls the semiconductor device 5 according to a signal supplied via the terminal 4, and output signals from the semiconductor devices 5 and 6 are delivered via the terminal 3.

[0015] A heat sink 12 is connected to the lower surface of the frame part 1. An insulating film 13 is arranged on the lower surface of the heat sink 12. The insulating film 13 consists of a composite material of epoxy resin and a filler. The filler consists of ceramic additive particles.

[0016] A sealing component 14 seals the frame part 1, the semiconductor devices 5 and 6, and the heat sink 12, thereby forming a module body 15. The sealing component 14 is made of epoxy resin or the like. The other end of each of the terminals 3 and 4 protrudes from a lateral surface of the module body 15. The lower surface of the insulating film 13 is exposed on the lower surface of the module body 15, excluding the sealing component 14. A copper foil or the like may be placed on the lower surface of the insulating film 13. The lower surface of the module body 15 serves as a heat dissipation surface. The heat dissipation surface is bonded to an external heat dissipation fin by a grease-like material.

[0017] The effects of the present embodiment, to explain the technical background of the present invention, are described below in comparison with a comparative example. Fig. Figure 2 is a cross-sectional view illustrating a semiconductor module according to a comparative example. In the comparative example, an insulating film 16 is positioned between the frame part 1 and the heat sink 12. Since the insulating film 16 is adjacent to the semiconductor devices as heat sources, it is exposed to a high temperature, essentially the same as the highest temperature of the semiconductor devices 5 and 6. Therefore, the insulating film 16 must exhibit high heat resistance, and the manufacturing costs increase accordingly. In the recent practical application of a SiC device, a highly heat-resistant insulating film is required for the structure of the comparative example. However, since the glass transition temperature of a resin composite material for the insulating film 16 is typically 160 to 170°C, achieving a sufficient improvement in heat resistance is challenging in terms of both technology and cost.In the embodiment for the purpose of explaining the technical background of the present invention, however, since the insulating film 13 is arranged on the lower surface of the heat sink 12, the insulating film 13 can be separated from the semiconductor devices 5 and 6 as heat-generating sources.

[0018] In the comparative example, the frame part 1 corresponds to one-tenth of the thermal resistance on a main heat dissipation path on the side of the lower surface of the module, and the insulating film 16 corresponds to nine-tenths of this. However, in the embodiment used to illustrate the technical background of the present invention, the frame part 1 corresponds to one-tenth of the thermal resistance on the main heat dissipation path, the heat sink 12 corresponds to three-tenths of this, and the insulating film 13 corresponds to six-tenths of this. Thus, in the embodiment used to illustrate the technical background of the present invention, the ratio corresponding to the insulating film 13 in the thermal resistance on the main heat dissipation path can be reduced.

[0019] Fig. Figure 3 is a diagram illustrating the relationship between the ratio of the heat sink thickness relative to the module body thickness and the temperature of the insulating film. The thermal resistance is estimated based on the thermal conductivity of the material of each layer between each of the semiconductor devices 5 and 6 as heat sources and the insulating film 13, and the thickness of the layer in the longitudinal direction, and the temperature of the insulating film 13 is calculated.

[0020] In a range where the ratio A / B of the thickness A of the heat sink 12 relative to the thickness B of the module body 15 is less than 50%, the temperature of the insulating film 13 decreases significantly with increasing thickness A of the heat sink 12. When the ratio A / B is equal to or greater than 50%, the decrease in the temperature of the insulating film 13 slows down. When the ratio A / B reaches 75%, the decrease in the temperature of the insulating film 13 reaches saturation.

[0021] Thus, in the embodiment used to explain the technical background of the present invention, the thickness A of the heat sink 12 is equal to or greater than 50% of the thickness B of the module body 15 (A / B ≥ 0.50), preferably equal to or greater than 75% (A / B ≥ 0.75). In other words, the insulating film 13 is sufficiently separated from the semiconductor devices 5 and 6, which act as heat sources, to intentionally increase the thermal resistance along a heat transfer path between the film and each device. Consequently, the ambient temperature of the insulating film 13 decreases, and thermal failure of the insulating film 13 can be prevented. Therefore, a highly heat-resistant insulating film is not required, and manufacturing costs can be reduced. Furthermore, power devices with a higher operating temperature than the semiconductor devices 5 and 6 can be mounted.

[0022] A heat flow from the semiconductor devices 5 and 6 is thermally diffused or distributed across the heat sink 12, which has a high heat capacity. In this case, heat transfer is balanced and released or dissipated from the heat-dissipating surface. In this way, the heat flow is temporarily accumulated in the thick heat sink 12 before being dissipated to the outside. Consequently, the ambient temperature of the insulating film 13, as described in the embodiment illustrating the technical background of the present invention and located on the lower surface of the heat sink 12, is approximately 20°C to 30°C lower than the ambient temperature of the insulating film 16, as described in the comparative example, which is located directly below the semiconductor devices 5 and 6. However, the temperature difference between the insulating films varies depending on the operating conditions and other factors.

[0023] Since, in the comparative example, the height of frame part 1 is lower than the heights of frame part 2 and the terminals 3 and 4, the sealing component 14 above frame part 1 is thick. Accordingly, the thermal resistance from the semiconductor devices 5 and 6, which are mounted on frame part 1, to the upper surface of the module is more than 10 times higher than the thermal resistance on a heat dissipation path on the lower surface of the module, and thus the upper surface of the module hardly functions as a heat dissipation path.

[0024] In the embodiment used to illustrate the technical background of the present invention, however, the terminals 3 and 4 and the frame parts 1 and 2 are at the same height. Accordingly, the sealing component 14 above the frame part 1 is thin, and the thermal resistance from the semiconductor devices 5 and 6 to the upper surface of the module can be reduced. As a result, the heat dissipation performance of the entire module can be improved. Since the frame part 1 is tall, this configuration is also effective in separating the insulating film 13 from the semiconductor devices 5 and 6, which act as heat sources.

[0025] The material of the heat sink 12 is aluminum, chosen for its cost and machinability. The material of the frame part 1 is, for example, copper. Accordingly, the thermal conductivity of the heat sink 12 is lower than that of the frame part 1. The thermal resistance R [m 2The thermal conductivity [W / (m·K)] is obtained using R = d / λ, where d and λ represent the thickness [m] and the thermal conductivity [W / (m·K)], respectively, of a thermal insulation material. Thus, the thermal resistance between each of the semiconductor devices 5 and 6, acting as heat sources, and the insulating film 13 is high, and consequently, the ambient temperature of the insulating film 13 can be reduced. The material of the heat sink 12 is preferably an alloy material with a lower thermal conductivity than aluminum. embodiment of the present invention

[0026] Fig. Figure 4 is a cross-sectional view illustrating a semiconductor module according to an embodiment of the present invention. The sealing component 14 comprises a first sealing component 14a, which is arranged on the side of the lower surface of the frame part 1, and a second sealing component 14b, which is arranged on the side of the upper surface of the frame part 1. A transition or connection interface 17 is present between the first sealing component 14a and the second sealing component 14b. The first sealing component 14a and the second sealing component 14b are directly connected to each other by the connection interface 17. The connection interface 17 can be detected optically or tested by analysis. The first sealing component 14a and the second sealing component 14b can be made of the same material or of different materials.

[0027] The first sealing component 14a covers the side surfaces of the heat sink 12 and the insulating film 13. Without the first sealing component 14a, the upper surface of the heat sink 12 is exposed and flush with the upper surface of the first sealing component 14a. The second sealing component 14b covers the upper and side surfaces of the frame parts 1 and 2 and the terminals 3 and 4, the semiconductor devices 5 and 6, the control element 7, and the wires 8 to 11. The lower surface of the second sealing component 14b is flush with the lower surfaces of the frame parts 1 and 2 and the terminals 3 and 4. Without the second sealing component 14b, the lower surface of the frame part 1 is exposed and contacts the upper surface of the heat sink 12.

[0028] The heat sink 12 has a trapezoidal cross-section, with the lower side closer to the insulating film 13 being longer than the upper side closer to the frame part 1. Thus, the area of ​​the upper surface of the heat sink 12, which receives heat from the semiconductor devices 5 and 6 as heat sources, is smaller than the area of ​​the lower surface of the heat sink 12, which dissipates heat to the external heat dissipation fin. Accordingly, the thermal resistance between each of the semiconductor devices 5 and 6 and the insulating film 13 can be further increased, and the rise in the ambient temperature of the insulating film 13 can be further reduced. Furthermore, heat is distributed over the entire heat sink 12, and thus the size of the heat sink 12 can be reduced. The remaining configuration is the same as in the embodiment used to explain the technical background of the present invention.

[0029] Fig. Figures 5 to 9 are cross-sectional views that illustrate a method for manufacturing the semiconductor module according to the embodiment of the present invention, in order to explain the technical background of the present invention. First, the insulating film 13 is applied to the lower surface of the heat sink 12 as shown in Fig. Figure 5 illustrates the arrangement. The heat sink 12 and the insulating film 13 are placed in a first form 18. Then, as shown in Figure 5, the heat sink 12 and the insulating film 13 are arranged. Fig. As illustrated in Figure 6, the first sealing component 14a is injected into the first mold 18 to seal the heat sink 12 and the insulating film 13 with the first sealing component 14a, thereby forming a lower part 15a of the module. As shown in Fig. As illustrated in Figure 7, the upper surface of the lower part 15a of the module is flat and the upper surface of the first sealing component 14a is flush with the upper surface of the heat sink 12.

[0030] Then, as in Fig. As illustrated in Figure 8, frame parts 1 and 2 and terminals 3 and 4 are placed at the same height on the upper surface of the lower part 15a of the module. Specifically, frame part 1 is placed on the upper surface of the heat sink 12, which is exposed without the first sealing component 14a. Semiconductor devices 5 and 6 are mounted on the upper surface of frame part 1. Semiconductor devices 5 and 6 are connected to terminals 3 and 4 by wires. The lower part 15a of the module, frame parts 1 and 2, terminal parts 3 and 4, and semiconductor devices 5 and 6 are placed in a second form 19.

[0031] Then, as in Fig.As illustrated in Figure 9, the second sealing component 14b is injected into the second mold 19 to seal the frame parts 1 and 2 and the semiconductor devices 5 and 6 with the second sealing component 14b, thereby forming an upper part 15b of the module. The semiconductor module is produced according to the embodiment of the present invention by the processes described above.

[0032] In a conventional case, the shaping process is carried out in one step after a chip is mounted on a frame component and bonded to a wire. An insulating film is bonded to the frame component using the temperature and pressure of a resin that cures during the shaping process.

[0033] In the embodiment of the present invention, however, the lower part 15a and the upper part 15b of the module are subjected to separate shaping processes. Thus, the resin material or shaping conditions can differ between the sealing component 14a and the second sealing component 14b. Accordingly, the resin material and the shaping conditions can be individually selected for each of the sealing components. As a result, the manufacturing process can be simplified, thereby reducing manufacturing costs. Furthermore, the process design for the shaping process of both the lower part 15a and the upper part 15b of the module can be optimized, which improves the manufacturing quality.

[0034] The upper surface of the lower part 15a of the module is preferably flat. This configuration allows the frame parts 1 and 2 and the connectors 3 and 4 to be positioned at the same height on the upper surface of the lower part 15a of the module. Similar to the embodiment described in the explanatory notes of the present invention, the thickness of the heat sink 12 is equal to or greater than 50% of the total thickness of the lower part 15a and the upper part 15b of the module, but preferably equal to or greater than 75%. Accordingly, the same effects as in the embodiment described in the explanatory notes of the present invention can be achieved. The manufacturing method according to the present embodiment is also applicable in a case where the heat sink 12 has a rectangular cross-section, as in the embodiment described in the explanatory notes of the present invention.

[0035] Semiconductor devices 5 and 6 are not limited to silicon-based semiconductor devices but can instead be formed from a wide-bandgap semiconductor with a larger bandgap than that of silicon. Examples of such wide-bandgap semiconductors include silicon carbide, gallium nitride-based materials, and diamond. A semiconductor device formed from such a wide-bandgap semiconductor exhibits high voltage withstand capability and high current density, and can therefore be miniaturized. The use of such a miniaturized semiconductor device enables the miniaturization and high integration of the semiconductor device in which it is integrated.Since the semiconductor device exhibits high heat resistance, a heat sink's heat sink fin can be miniaturized, and a water-cooled component can be air-cooled, leading to further miniaturization of the semiconductor device. Furthermore, since the semiconductor device has low power loss and high efficiency, a highly efficient semiconductor device can be achieved. (Supplementary note 1)

[0036] A semiconductor module comprising: a frame part; a semiconductor device mounted on an upper surface of the frame part; a heat sink that is connected to a lower surface of the frame part; an insulating film arranged on a lower surface of the heat sink; and a sealing component that seals the frame part, the semiconductor device and the heat sink to form a module body, where the thickness of the heat sink is equal to or greater than 50% of the thickness of the module body. (Supplementary note 2)

[0037] The semiconductor module according to Supplementary Note 1, wherein the thickness of the heat sink is equal to or greater than 75% of the thickness of the module body. (Supplementary note 3)

[0038] The semiconductor module according to Supplementary Note 1 or 2, wherein the sealing component comprises a first sealing component arranged on one side of a lower surface of the frame part and a second sealing component arranged on one side of an upper surface of the frame part, and a connecting interface exists between the first sealing component and the second sealing component. (Supplementary note 4)

[0039] The semiconductor module according to one of the supplementary notes 1 to 3, further comprising a connection having one end connected to the semiconductor device and the other end protruding from a lateral surface of the sealing component, where the connection and the frame part are at the same height. (Supplementary note 5)

[0040] The semiconductor module according to one of Supplementary Notes 1 to 4, wherein the heat sink has a trapezoidal cross-section in which a lower side closer to the insulating film is longer than an upper side closer to the frame part. (Supplementary note 6)

[0041] The semiconductor module according to one of the supplementary notes 1 to 5, wherein the thermal conductivity of the heat sink is lower than the thermal conductivity of the frame part. (Supplementary note 7)

[0042] The semiconductor module according to one of the supplementary notes 1 to 6, wherein the insulating film is made of a composite material of resin and a filler. (Supplementary note 8)

[0043] The semiconductor module according to one of the supplementary notes 1 to 7, wherein the semiconductor device is formed from a wide bandgap semiconductor. (Supplementary note 9)

[0044] A method for manufacturing a semiconductor module, comprising: an arrangement of an insulating film on a lower surface of a heat sink; a placement of the heat sink and insulating film in a first form and a sealing of the heat sink and insulating film with a first sealing component to form a lower part of the module; placing a frame component on an upper surface of the heat sink that is exposed without the first sealing component; mounting a semiconductor device on an upper surface of the frame part; and a placement of the lower part of the module, the frame part and the semiconductor device in a second mold and a sealing of the frame part and the semiconductor device with a second sealing component to form an upper part of the module. (Supplementary note 10)

[0045] The method for manufacturing a semiconductor module according to Supplementary Note 9, wherein a resin material or a shaping condition differs between the first sealing component and the second sealing component. (Supplementary note 11)

[0046] The method for manufacturing a semiconductor module according to Supplementary Note 9 or 10, wherein an upper surface of the lower part of the module is flat, the frame part and a connector are placed on an upper surface of the lower part of the module and The semiconductor device is connected to the terminal by a wire and sealed with a second sealing component. (Supplementary note 12)

[0047] The method for manufacturing a semiconductor module according to one of Supplementary Notes 9 to 11, wherein the thickness of the heat sink is equal to or greater than 50% of the total thickness of the lower part of the module and the upper part of the module. (Supplementary note 13)

[0048] The method for manufacturing a semiconductor module according to one of Supplementary Notes 9 to 11, wherein the thickness of the heat sink is equal to or greater than 75% of the total thickness of the lower part of the module and the upper part of the module.

Claims

[1] Semiconductor module, comprising: - a frame part (1, 2); - a semiconductor device (5, 6) mounted on an upper surface of the frame part (1); - a heat sink (12) connected to a lower surface of the frame part (1); - an insulating film (13) arranged on a lower surface of the heat sink (12); and - a sealing member (14) which seals the frame part (1, 2), the semiconductor device (5, 6) and the heat sink (12) to form a module body (15), wherein: - a thickness (A) of the heat sink (12) is equal to or greater than 50% of a thickness (B) of the module body (15) and - the heat sink (12) has a trapezoidal cross-section in which a lower side closer to the insulating film (13) is longer than an upper side closer to the frame part (1). [2] Semiconductor module according to claim 1, wherein the thickness (A) of the heat sink (12) is equal to or greater than 75% of the thickness (B) of the module body (15). [3] A semiconductor module according to claim 1 or 2, wherein: - the sealing member (14) comprises a first sealing member (14a) arranged on one side of a lower surface of the frame part (1, 2) and a second sealing member (14b) arranged on one side of an upper surface of the frame part (1), and - a connecting interface (17) is present between the first sealing component (14a) and the second sealing component (14b). [4] Semiconductor module according to claim 1 or 2, - further comprising a terminal (3, 4) having one end connected to the semiconductor device (5, 6) and the other end protruding from a lateral surface of the sealing member (14), - wherein the connection (3, 4) and the frame part (1, 2) are at the same height. [5] Semiconductor module according to claim 1 or 2, wherein the thermal conductivity of the heat sink (12) is lower than the thermal conductivity of the frame part (1). [6] A semiconductor module according to claim 1 or 2, wherein the insulating film (13) is made of a composite material of resin and a filler. [7] A semiconductor module according to claim 1 or 2, wherein the semiconductor device (5, 6) is formed of a wide band gap semiconductor.

Images