Semiconductor device

Abstract

A semiconductor device 100 comprises a base plate 1, an insulation substrate 5, two or three plate-shaped semiconductor chips 7, an electrode member 9, and a sealing resin body 17 that: is stacked on the upper surface of the base plate 1; covers all of a first solder layer 2, the insulation substrate 5, a second solder layer 6, the semiconductor chips 7, a third solder layer 8, and the electrode member 9; and has a lower end part affixed to the base plate 1. On the upper surface of the base plate 1, a pair of affixing spaces 21 and the two or three plate-shaped semiconductor chips 7 are aligned in a predetermined direction 23. Along the predetermined direction 23, the base plate 1 has protrusions at portions positioned under each of the two or three plate-shaped semiconductor chips 7 and is warped so as to project downward.

Description

Semiconductor device 【0006】 , 【0005】 , 【0001】 The present invention relates to a semiconductor device. 【0002】 This application claims the benefit of foreign priority to Japanese Patent Application No. JP2024 - 215043, filed December 10, 2024, which is incorporated by reference in its entirety. Conventionally, power semiconductor devices are known. A power semiconductor device is required to have good heat dissipation. As such a power semiconductor device, for example, the semiconductor device described in JP2020 - 115568 is known. This semiconductor device is used by being attached to a cooler. The insulating substrate on which semiconductor elements are arranged is warped so as to be convex on the side of the cooler, thereby improving the adhesion between the insulating substrate and the cooler, and thus improving the heat dissipation of the semiconductor device to the cooler. 【0003】 JP2020 - 115568 【0004】 By the way, there is a type of semiconductor device in which an insulating substrate on which semiconductor chips (semiconductor elements) are arranged is arranged on a metal base plate for heat conduction, and this base plate is attached to the cooling surface of a cooling mechanism. There was room for further improvement in heat dissipation in this type of semiconductor device. 【0005】 The present invention has been made to solve the above problems, and is a semiconductor device in which an insulating substrate on which semiconductor chips are arranged is arranged on a metal base plate for heat conduction, and an object thereof is to provide a semiconductor device capable of improving the heat dissipation from the semiconductor chips to the cooling mechanism. 【0006】To achieve the above objective, a semiconductor device according to one aspect of the present disclosure comprises a metal base plate for heat conduction, an insulating substrate having a lower copper layer and an upper copper layer formed on the lower and upper surfaces of a tough ceramic substrate, soldered to the upper surface of the base plate at the lower copper layer by a first solder layer, two or three plate-shaped semiconductor chips soldered to the upper copper layer of the insulating substrate at the lower surface by a second solder layer, electrode members soldered to the upper surface of each of the two or three plate-shaped semiconductor chips at the lower surface by a third solder layer, and the first solder layer stacked on the upper surface of the base plate. The device comprises the insulating substrate, the second solder layer, the two or three plate-shaped semiconductor chips, the third solder layer, and a sealing resin body that covers part or all of the electrode member and whose lower end is fixed to the base plate, wherein the insulating substrate is fixed to the upper surface of the base plate, and in a predetermined direction, has a pair of fixing spaces between the base plate and both ends of the base plate for fixing the base plate to the cooling surface of the cooling mechanism, the pair of fixing spaces and the two or three plate-shaped semiconductor chips are aligned in the predetermined direction, and the base plate is curved so that it has a convex portion that protrudes downward in the predetermined direction, below each of the two or three plate-shaped semiconductor chips. 【0007】 The present invention provides a semiconductor device in which an insulating substrate on which a semiconductor chip is arranged is placed on a metal base plate for heat conduction, and which has the effect of providing a semiconductor device that can improve heat dissipation from the semiconductor chip to the cooling mechanism. 【0008】Figure 1 is a perspective view showing an example of the appearance of a semiconductor device according to Embodiment 1 of this disclosure. Figure 2 is an exploded view showing an example of the configuration of the semiconductor device of Figure 1. Figure 3 is a longitudinal cross-sectional view showing a cross-section of the semiconductor device of Figure 1 cut along the line A-A in Figure 2. Figure 4A is a process diagram showing the process of creating an insulating substrate assembly in the manufacturing of the semiconductor device of Figure 1. Figure 4B is a process diagram showing the process of soldering a base plate, electrode members, power supply terminals, etc. to the insulating substrate assembly obtained in the process of Figure 4A. Figure 4C is a process diagram showing the process of attaching a resin case to the semi-finished product obtained in the process of Figure 4B. Figure 4D is a process diagram showing the process of covering the main part of the semi-finished product obtained in the process of Figure 4C with a gel-like resin body. Figure 4E is a process diagram showing the process of sealing the semi-finished product obtained in the process of Figure 4D with an epoxy resin body. Figure 4F is a process diagram showing the process of bending the power supply terminals of the semi-finished product obtained in the process of Figure 4E. Figure 5A is a graph showing the curvature of the base plate of the semiconductor device of Figure 1. Figure 5B is a graph showing the typical warping pattern of the base plate of a specific type of semiconductor device. Figure 6 is a diagram showing how the semiconductor device of the embodiment is attached to the cooling surface of a heat dissipation substrate as a cooling mechanism. Figure 7 is a graph showing the measured amount of warping of the base plate of the semiconductor device before it is attached to the cooling surface of the heat dissipation substrate as a cooling mechanism in the embodiment. Figure 8A is a graph showing the measured amount of warping of the base plate of the semiconductor device that is loosely fastened with bolts to the cooling surface of the heat dissipation substrate as a cooling mechanism in the embodiment. Figure 8B is a graph showing the measured amount of warping of the base plate of the semiconductor device that is firmly fastened with bolts to the cooling surface of the heat dissipation substrate as a cooling mechanism in the embodiment. Figure 9A is a graph conceptually showing the warping pattern of the base plate of a conventional semiconductor device before it is attached to the cooling surface of a heat dissipation substrate as a cooling mechanism. Figure 9B is a graph conceptually showing the warping pattern of the base plate of a conventional semiconductor device that is loosely fastened with bolts to the cooling surface of a heat dissipation substrate as a cooling mechanism. Figure 9C is a conceptual graph showing the curvature of a base plate of a conventional semiconductor device that is firmly fastened with bolts to the cooling surface of a heat dissipation substrate as a cooling mechanism. Figure 10 is a longitudinal cross-sectional view of a semiconductor device according to Embodiment 2 of the present disclosure. 【0009】(Knowledge that led to the present invention) The inventors measured the curvature of a base plate using a laser displacement sensor in order to examine the heat dissipation performance to a cooling mechanism of a semiconductor device of the type in which an insulating substrate on which semiconductor elements are arranged is placed on a metal base plate for heat conduction (sometimes referred to as a "specific type of semiconductor device" in this specification). As shown in Figure 5B, the base plate of a typical specific type of semiconductor device before attachment to the cooling mechanism was convex in the direction from the main surface on which the main part of the semiconductor device is provided (hereinafter referred to as the upper surface) to the opposite main surface (hereinafter referred to as the lower surface) (hereinafter referred to as downward). More specifically, the base plate was curved downward so that the curvature decreased from both ends towards the center. Hereinafter, this curvature of a plate-shaped object so that the curvature decreases from both ends towards the center will simply be described as a plate-shaped object "curving". 【0010】 When this semiconductor device was attached to the cooling surface (mounting surface) of the cooling mechanism by fixing both ends of the base plate with bolts, the base plate curved in the opposite direction. The reason for this is thought to be that when the base plate, which is curved toward the cooling surface of the cooling mechanism, is attached to the flat cooling surface of the cooling mechanism by fixing both ends while pressing them with bolts, the base plate is fixed at approximately the length of its curved state, and because the base plate is made of metal and is elastic, the portion between the fixed parts at both ends separates from the flat cooling surface and curves in the opposite direction (see Figures 9B and 9C). In this reverse-curved state, the base plate separates more and more from the cooling surface as it moves from the edges toward the center, reducing the heat dissipation from the semiconductor chip located above the center of the base plate to the cooling mechanism. 【0011】 As a result, it was found that the objective of improving the adhesion between the base plate and the cooling surface, and consequently improving the heat dissipation to the cooling mechanism of a specific type of semiconductor device, by curving the base plate toward the cooling surface of the cooling mechanism, was not fully achieved. 【0012】Therefore, the inventors conceived of curving the base plate so that it has a protrusion in the portion located below the semiconductor chip, thereby suppressing the separation of the portion of the base plate located below the semiconductor chip from the cooling surface of the cooling mechanism, and ultimately improving the heat dissipation from the semiconductor chip to the cooling mechanism. 【0013】 This invention is based on such findings. 【0014】 Therefore, a semiconductor device according to one aspect of the present disclosure comprises a metal base plate for heat conduction, an insulating substrate having a lower copper layer and an upper copper layer formed on the lower and upper surfaces of a tough ceramic substrate, an insulating substrate soldered to the upper surface of the base plate at the lower copper layer by a first solder layer, two or three plate-shaped semiconductor chips soldered to the upper copper layer of the insulating substrate at the lower surface by a second solder layer, electrode members soldered to the upper surface of each of the two or three semiconductor chips at the lower surface by a third solder layer, and the first solder layer and the insulating layer stacked on the upper surface of the base plate. The insulating substrate comprises a substrate, the second solder layer, the two or three plate-shaped semiconductor chips, the third solder layer, and a sealing resin body that covers part or all of the electrode member and whose lower end is fixed to the base plate, wherein the insulating substrate is fixed to the upper surface of the base plate, and in a predetermined direction, has a pair of fixing spaces between the base plate and both ends of the base plate for fixing the base plate to the cooling surface of the cooling mechanism, the pair of fixing spaces and the two or three plate-shaped semiconductor chips are aligned in the predetermined direction, and the base plate is curved so that it has a convex portion that protrudes downward in the predetermined direction, below each of the two or three semiconductor chips. 【0015】In this configuration, each of the two or three plate-shaped semiconductor chips has a convex portion located below it in a predetermined direction, causing it to curve downwards. Therefore, when both ends of the base plate (fixing space) are fixed to the cooling surface, the base plate curves in the opposite direction due to its elasticity. However, because the portion located below the semiconductor chip has a convex portion, that portion is brought closer to the cooling surface, improving heat dissipation from the semiconductor chip to the cooling mechanism. 【0016】 The sealing resin body may include a resin case whose lower end is fixed to the base plate so as to cover part or all of the first solder layer, the insulating substrate, the second solder layer, the two or three plate-shaped semiconductor chips, the third solder layer, and the electrode member, which are stacked on the upper surface of the base plate, and a sealing resin layer formed inside the resin case so as to cover part or all of the first solder layer, the insulating substrate, the second solder layer, the two or three plate-shaped semiconductor chips, the third solder layer, and the electrode member, which are stacked on the upper surface of the base plate. 【0017】 This configuration makes it possible to improve heat dissipation from the semiconductor chip to the cooling mechanism in a semiconductor device equipped with a potting-type sealing resin body. 【0018】 The sealing resin body may be a molded sealing resin body that is stacked on the upper surface of the base plate, covering part or all of the first solder layer, the insulating substrate, the second solder layer, the two or three plate-shaped semiconductor chips, the third solder layer, and the electrode members, and whose lower end is fixed to the base plate. 【0019】 This configuration makes it possible to improve heat dissipation from the semiconductor chip to the cooling mechanism in a semiconductor device equipped with a transfer-type sealing resin body. 【0020】 The base plate may have a shape that extends in the predetermined direction, and the lower end of the resin case may be fixed to the base plate such that it reaches both ends of the base plate. 【0021】 This configuration allows for the adjustment of the amount of warping of the base plate. 【0022】 The amount of warping of the base plate may be on the order of micrometers. 【0023】 This configuration allows the base plate to be in good contact with the cooling surface of the cooling mechanism. 【0024】 The material of the base plate may be copper or aluminum. 【0025】 This configuration allows for improved thermal conductivity of the base plate. 【0026】 Specific embodiments of this disclosure will be described below with reference to the drawings. In the following, the same or corresponding elements are denoted by the same reference numerals throughout all drawings, and redundant explanations are omitted. Furthermore, since the following figures are for illustrative purposes of this disclosure, elements unrelated to this disclosure may be omitted, dimensions may be inaccurate due to exaggeration, simplifications may occur, and the forms of corresponding elements may not match across multiple figures. Also, this disclosure is not limited to the following embodiments. 【0027】 (Definitions) For convenience, in the specification and claims of this application, the main surface of the base plate 1 on which the main part 32 of the semiconductor device is provided is called the "top surface," and the main surface opposite the "top surface" is called the "bottom surface." Also, the direction from the "bottom surface" of the base plate 1 toward the "top surface" is called the "upward direction" or "upper direction," and the direction from the "top surface" of the base plate 1 toward the "bottom surface" is called the "downward direction" or "downward direction" (see Figures 3 and 10). 【0028】 (Summary of the Disclosure) In this disclosure, an embodiment is provided in which a sealing resin body 17 is provided on the upper surface of a base plate 1, covering the main parts 32 of semiconductor devices 100, 200 and having its lower end fixed to the base plate 1. Of these embodiments, an embodiment in which the sealing resin body 17 is a potting type sealing resin body is provided as Embodiment 1, and an embodiment in which the sealing resin body 17 is a transfer type molded sealing resin body is provided as Embodiment 2. Embodiments 1 and 2 will be described in order below. 【0029】 (Embodiment 1) 【0030】 [Configuration] The configuration of the semiconductor device 100 according to Embodiment 1 will be described below in the order of mechanical configuration, electrical configuration, and materials of each element. In the following description, a configuration in which the semiconductor device 100 has two semiconductor chips 7, 7 will be described, but a configuration in which the semiconductor device 100 has three semiconductor chips can also be easily inferred from the following description. 【0031】 {Mechanical Configuration} Figure 1 is a perspective view showing an example of the external appearance of a semiconductor device 100 according to an embodiment of the present disclosure. Referring to Figure 1, the semiconductor device 100 of the present disclosure is a specific type of semiconductor device and includes a metal base plate 1 for heat conduction. The lower end of a resin case 10, which has an open bottom, is fixed to the upper surface of the base plate 1. The resin case 10 is formed in an elongated shape (for example, a rectangular parallelepiped), and both ends in the longitudinal direction are formed in a U shape. The resin case 10 covers the upper surface of the base plate 1 except for the central part of these U-shaped ends. In other words, the lower end of the resin case 10 is fixed to the base plate 1 so as to extend to both ends of the base plate 1. Both ends of the base plate 1 are fixing spaces 21, and mounting holes 22 are provided in the portion of these fixing spaces 21 that is not covered by the resin case 10 for attaching the base plate 1 to the cooling surface 51a of a heat dissipation substrate 51 (see Figure 6) as a cooling mechanism. The mounting hole 22 is formed as a through hole through which a mounting bolt 61 (see Figure 6) can be inserted. The main part 32 of the semiconductor device 100 (see Figure 3) is housed inside the resin case 10, and three power supply terminals 11, 11, 11 are exposed in the center of the upper surface of the resin case 10, and a pair of sockets (receptacles) 13, 13 are provided at one end of the upper surface of the resin case 10, with the tips of pin members 12, 12 exposed inside the pair of sockets 13, 13, respectively. 【0032】Figure 2 is an exploded view showing an example of the configuration of the semiconductor device 100 shown in Figure 1. In Figure 2, the resin case 10 and the sealing resin layer 15 (see Figure 3) are omitted. Referring to Figure 2, the main components of the semiconductor device 100, excluding the resin case 10 and the sealing resin layer 15, include a base plate 1, a first solder plate 2a (first solder layer 2 in Figure 3), an insulating substrate 5, a pair of electrode members 9, 9, three power supply terminals 11, 11, 11, a pair of pin members 12, 12 (one of which is omitted in Figure 2), and a wiring member 14. The base plate 1 is formed in an elongated shape (for example, rectangular), and the longitudinal direction of the base plate 1 (the direction in which the base plate 1 extends) is called the predetermined direction 23. On the base plate 1, two plate-shaped semiconductor chips 7, 7 and a pair of fixed spaces 21 are arranged in the predetermined direction 23. The two plate-shaped semiconductor chips 7, 7 are arranged to have a predetermined space 31 in the predetermined direction 23. The fixed space 21 is provided on both sides of the two semiconductor chips 7, 7. The pair of pin members 12 are not directly related to this disclosure, so one of the pin members 12 is not shown in Figure 2, and its configuration will be briefly described. The pin member 12 includes a resin body 12a, a pair of metal pins 12b extending upward from the body 12a, and a metal wiring portion 12c extending laterally from the body 12a. The pair of pins 12b and the wiring portion 12c are electrically connected. 【0033】 Figure 3 is a longitudinal cross-sectional view showing the semiconductor device 100 of Figure 1 cut along the line A-A in Figure 2. In Figure 3, the actual dimensions are exaggerated vertically to make the longitudinal cross-sectional structure of the semiconductor device 100 easier to understand. Also, the shapes of the two electrode members 9, 9 are simplified in Figure 3. 【0034】Referring to Figure 3, in the semiconductor device 100, an insulating substrate 5 is arranged on a base plate 1 such that it has fixing spaces 21 on both sides in a predetermined direction 23. The insulating substrate 5 comprises a tough ceramic substrate 3, a lower copper layer 4a formed on the lower surface of the ceramic substrate 3, and an upper copper layer 4b formed on the upper surface of the ceramic substrate 3. The lower copper layer 4a is formed in the shape of a single plate. The upper copper layer 4b is patterned to constitute a predetermined circuit (see Figure 2). The insulating substrate 5 is soldered to the upper surface of the base plate 1 at the lower copper layer 4a by a first solder layer 2. Two plate-shaped semiconductor chips 7, 7 are soldered to the upper copper layer 4b of the insulating substrate 5 at their respective lower surfaces by a second solder layer 6. Two plate-shaped electrode members 9, 9 are soldered to the upper surfaces of these two semiconductor chips 7, 7 at their respective lower surfaces by a third solder layer 8, 8. 【0035】 The first solder layer 2, insulating substrate 5, second solder layer 6, two semiconductor chips 7, 7, third solder layers 8, 8, and two electrode members 9, 9, all stacked on the upper surface of the base plate 1, constitute the main part (hereinafter sometimes simply referred to as the "main part") 32 of the semiconductor device 100. This main part 32 is covered by a resin case 10. The resin case 10 is open at the bottom and its lower end is fixed to the base plate 1 with adhesive. 【0036】 The resin case 10 is filled with a gel-like resin body 15a that almost completely covers the main part 32. Furthermore, a cured epoxy resin body 15b is provided inside the resin case 10 to cover the gel-like resin body 15a and the upper part of the main part 32 that is exposed from the gel-like resin body 15a. These gel-like resin body 15a and cured epoxy resin body 15b constitute a sealing resin layer 15. The sealing resin layer 15 and the resin case 10 constitute a potting-type sealing resin body 17. 【0037】{Electrical Configuration} Referring to Figures 1 to 3, the two semiconductor chips 7, 7 are composed of semiconductor elements, for example. For example, the semiconductor chip 7 on the left and the semiconductor chip 7 on the right in Figure 2 are composed of a diode and a thyristor, respectively. The three power supply terminals 11, 11, 11 and the two electrode members 9, 9 are soldered to the patterned upper copper layer 4b of the insulating substrate 5 as appropriate to supply power to the semiconductor elements of the two semiconductor chips 7, 7 through the three power supply terminals 11, 11, 11. In general semiconductor devices, power is supplied to the semiconductor chips 7, 7 through wire bonding, but in this embodiment 1, plate-shaped electrode members 9, 9 are used to avoid wire breakage in wire bonding. The electrode members 9, 9 here have a shape in which a plate material is bent, but their shape is not particularly limited. The pair of pin members 12, 12 and the wiring member 14 are soldered to the patterned upper copper layer 4b of the insulating substrate 5 as appropriate, for example, to supply control signals to the semiconductor elements of two semiconductor chips 7, 7. The three power supply terminals 11, 11, 11 are each bent as appropriate so as to extend upward from through holes in the upper surface of the resin case 10 and abut against the upper surface of the resin case 10. The pins 12b, 12b of the pair of pin members 12, 12 are each exposed inside a pair of sockets 13, 13 provided at one end of the upper surface of the resin case 10, and each constitutes an electrical contact with a plug inserted into the sockets 13, 13. Note that an electrode member 9 and a power supply terminal 11 may be integrally formed. 【0038】{Materials of Each Element} The material of the base plate 1 is metal, and examples of this metal include copper or aluminum. The materials of the first solder layer 2, the second solder layer 6, and the third solder layer 8 are plate-shaped solder and are not particularly limited. The insulating substrate 5 is constituted of, for example, a DBC (Direct Bonded Copper) substrate. The material of the electrode member 9 is, for example, metal, and examples of this metal include copper or aluminum. The material of the resin case 10 is, for example, plastic. The material of the power supply terminal 11 is, for example, metal, and examples of this metal include copper or aluminum. As an adhesive for bonding the resin case 10 to the base plate 1, silicone rubber is exemplified. 【0039】 The pin member 12 includes a resin main body 12a having an appropriate shape, a pair of pins 12b, 12b extending from the main body 12a, and a wiring portion 12c. The materials of the pins 12b and the wiring portion 12c are, for example, metal, and examples of this metal include copper or aluminum. 【0040】 As the material of the gel-like resin body 15a, silicone gel is exemplified. As the material of the epoxy resin body 15b, epoxy resin is exemplified. 【0041】 [Manufacturing Method] Next, the manufacturing method of the semiconductor device 100 configured as described above will be described in order for each process. 【0042】 FIG. 4A is a process diagram showing the process of creating the insulating substrate assembly 41 in the manufacture of the semiconductor device 100 of FIG. 1. 【0043】 Referring to FIG. 4A, in this process, first, the insulating substrate 5 is prepared. The insulating substrate 5 is flat and not warped particularly. 【0044】 Next, two plate-shaped semiconductor chips 7, 7 are soldered to predetermined pads of the upper surface copper layer 4b of the insulating substrate 5 by second plate solders 6a, 6a for forming the second solder layers 6, 6 (see FIG. 3) respectively. The conditions for this soldering are general. Thereby, the insulating substrate assembly 41 is obtained. 【0045】FIG. 4B is a process diagram showing a process of soldering elements such as the base plate 1, the electrode members 9, 9, and the power supply terminals 11, 11, 11 to the insulating substrate assembly 41 obtained in the process of FIG. 4A. 【0046】 Referring to FIG. 4B, in this process, first, the base plate 1 is prepared. The base plate 1 is warped so as to curve downward. The amount of warp of the base plate 1 is determined according to the amount of warp of the base plate 1 of the final semiconductor device 100. Specifically, it is determined to be larger than the amount of warp of the base plate 1 of the final semiconductor device 100 and not too far from the amount of warp of the base plate 1 of the final semiconductor device 100. The specific amount of warp of the base plate 1 is determined by experiments, simulations, etc. according to the specifications of the semiconductor device 100. The process of warping the base plate 1 so as to curve downward is not particularly limited. As the process of warping the base plate 1, known processes for insulating substrates of the type described in the prior art can be used. For example, a process of bending a flat base plate 1 by machining or a combination of machining and heat treatment can be mentioned. Both ends of the base plate 1 are fixed spaces 21, 21, and a pair of mounting holes 22, 22 are provided in this pair of fixed spaces 21, 21. 【0047】 Next, the insulating substrate assembly 41 obtained in the process of FIG. 4A is attached to the portion between the pair of fixed spaces 21, 21 on the upper surface of the base plate 1. Specifically, the lower copper layer 4a (see FIG. 3) of the insulating substrate 5 of the insulating substrate assembly 41 is soldered by the first plate solder 2a for forming the first solder layer 2. The conditions for this soldering are general. 【0048】 Next, electrode members 9, 9 are soldered to the upper surfaces of the two semiconductor chips 7, 7 by the third plate solder for forming the third solder layers 8, 8 (see FIG. 3). Thereby, the main part 32 is formed on the base plate 1. 【0049】Next, three power supply terminals 11, 11, 11, a pair of pin members 12, 12 (one of which is omitted in Figure 4B), and a wiring member 14 are soldered to predetermined pads on the upper copper layer of the insulating substrate 5 as appropriate. The conditions for these soldering are general. 【0050】 Figure 4C is a process diagram showing the process of attaching the resin case 10 to the semi-finished product obtained in the process of Figure 4B. Figures 4C, as well as Figures 4D and 4E described later, show a cross-section of the semi-finished product with the resin case 10 attached, cut along a plane that extends vertically and along the front side edge of the insulating substrate 5 in Figure 4B. 【0051】 Referring to Figure 4C, in this step, the resin case 10 is mounted on the upper surface of the base plate 1 from above the main part 32, the three power supply terminals 11, 11, 11, the pair of pin members 12, 12, and the wiring member 14 formed on the base plate 1. As a result, the main part 32, the lower part of the three power supply terminals 11, 11, 11, most of the pair of pin members 12, 12, and the wiring member 14 are covered by the resin case 10, the upper parts of the three power supply terminals 11, 11, 11 are exposed through the respective through holes on the upper surface of the resin case 10, and the tips of the pins (12a, 12a), (12a, 12a) of the pair of pin members 12, 12 are exposed inside the pair of sockets 13, 13 on the upper surface of the resin case 10. The resin case 10 is mounted on the base plate 1 by fixing (adhering) its lower end to the base plate 1 with an adhesive. This adhesive is cured by heating. 【0052】 Figure 4D is a process diagram showing the process of covering the main part 32 of the semi-finished product obtained in the process of Figure 4C with a gel-like resin body 15a. 【0053】 Referring to Figure 4D, in this process, first, resin for forming a gel-like resin body 15a is injected into the resin case 10 through a predetermined resin injection hole (not shown) in the resin case 10. This resin is a highly fluid gel. This gel-like resin is injected so as to substantially cover the base plate 1 and the main part 32. 【0054】Next, the entire semi-finished product is heated to a predetermined temperature, increasing the viscosity of the injected gel-like resin to the point where the resin does not flow out even when the resin case 10 is turned upside down. As a result, a gel-like resin body 15a is formed inside the resin case 10 so as to substantially cover the base plate 1 and the main part 32. 【0055】 Figure 4E is a process diagram showing the process of sealing the semi-finished product obtained in the process of Figure 4D with epoxy resin 15b. 【0056】 Referring to Figure 4E, in this step, first, epoxy resin for forming the epoxy resin body 15b is injected into the resin case 10 through a predetermined resin injection hole in the resin case 10. This epoxy resin is injected so as to cover the gel-like resin body 15a. 【0057】 Next, the entire semi-finished product is heated to a predetermined temperature, and the injected epoxy resin hardens. This forms an epoxy resin body 15b inside the resin case 10 that seals the base plate 1, the main part 32, and the gel-like resin body 15a. As a result, a sealing resin layer 15 is formed inside the resin case 10, and a sealing resin body 17, composed of the resin case 10 and the sealing resin layer 15, is formed on the upper surface of the base plate 1. 【0058】 Figure 4F is a process diagram showing the process of bending the power supply terminals 11, 11, 11 of the semi-finished product obtained in the process shown in Figure 4E. 【0059】 Referring to Figure 4F, in this step, the upper parts of the three power supply terminals 11, 11, 11 that protrude from the top surface of the resin case 10 in the semi-finished product obtained in the step of Figure 4E are bent so that they contact the top surface of the resin case 10. This completes the semiconductor device 100. 【0060】 [Warping of the base plate 1] Next, we will describe the warping of the base plate 1 in the semiconductor device 100 configured and manufactured as described above. 【0061】Figure 5A is a graph showing the curvature of the base plate 1 of the semiconductor device 100 in a predetermined direction (longitudinal direction) 23 shown in Figure 1. In Figure 5A, the horizontal axis represents the position (mm) in the predetermined direction 23 with respect to one end of the base plate 1, and the vertical axis represents the distance (μm) from a predetermined reference plane to the lower surface of the base plate 1. In Figure 5A, the downward direction represents the upward direction on the base plate 1. The amount of curvature was measured using a laser displacement sensor. 【0062】 Referring to Figure 5A, the base plate 1 is curved so that it protrudes downward in a predetermined direction 23, with convex portions 71 located below each of the two semiconductor chips 7, 7. More specifically, the downward-protruding shape of the base plate 1 has two convex portions 71, 71 located below the two semiconductor chips 7, 7, and a recess 72 located in the space 31 between these two convex portions, in other words, below the space 31 between the two semiconductor chips 7, 7 (see Figure 7). If the semiconductor device 100 has three semiconductor chips, similarly, the base plate 1 is curved so that it protrudes downward in a predetermined direction 23, with convex portions located below each of the three semiconductor chips. More specifically, the downward-protruding shape of the base plate 1 has convex portions located below each of the three semiconductor chips, and recesses located in the spaces between these three convex portions. In this case, these two recesses are smaller than the recess 72 when the semiconductor device 100 has two semiconductor chips 7, 7. 【0063】 It should be noted that the warp of the base plate 1 is on the order of micrometers. For example, the warp of the base plate 1 in the embodiment described later is 80 μm. Therefore, the warp of the base plate 1 cannot be recognized by visual inspection. The warp of the base plate 1 can be recognized, for example, by placing the semiconductor device 100 on the surface of a horizontal table and rotating the semiconductor device 100 by hand around its vertical central axis. 【0064】Figure 5B is a graph showing the longitudinal curvature of a base plate of a typical specific type of semiconductor device (conventional example). In Figure 5B, the horizontal axis represents the position (mm) in the longitudinal direction relative to one end of the base plate, and the vertical axis represents the distance (μm) from a predetermined reference plane on the lower surface of the base plate. In Figure 5B, the downward direction represents the upward direction of the base plate. The amount of curvature was measured by a laser displacement sensor. Referring to Figure 5B, the base plate is curved downwards. 【0065】 As is clear from comparing it with the curvature of the base plate 1 of the semiconductor device 100 in this embodiment, the base plate 1 has an original form of curvature (hereinafter sometimes referred to as a predetermined form) as shown in Figure 5B of a typical specific type of semiconductor device (conventional example). The effects of the base plate 1 of the semiconductor device 100 in this embodiment having this original form of curvature will be described in detail in the embodiments described later. 【0066】 [Points for bending the base plate 1 into a predetermined shape] The points for bending the base plate 1 into a predetermined shape are as follows. 【0067】 The first point is to bend the base plate 1 so that it curves downwards. 【0068】 The second point is that the main part 32, which is stacked on the upper surface of the base plate 1, is equipped with electrode members 9, 9 that are soldered to the upper surfaces of the plate-shaped semiconductor chips 7, 7, respectively. As a result, the base plate 1 curves so that it protrudes downward with a flat or recessed portion at its top. In other words, the shape of the curve that protrudes downward from the base plate 1 is generally trapezoidal. 【0069】 The third point is that the semiconductor device 100 includes a sealing resin body 17 fixed to the base plate 1. The form of the sealing resin body 17 fixed to the base plate 1 has a significant effect on the amount of warping of the base plate 1. 【0070】The fourth point is that the curvature of the base plate 1 can be controlled by adjusting the heat treatment conditions in the manufacturing process of the semiconductor device 100. The base plate 1, main part 32, and sealing resin body 17 as a whole include elements made of metal material with a high coefficient of thermal expansion and elements made of resin material with a low coefficient of thermal expansion. Therefore, each time the base plate 1, main part 32, and sealing resin body 17 are heated to a high temperature in a certain curvature state during the manufacturing process and then returned to room temperature, the combined effect of the thermal expansion coefficients of each element results in a curvature state. As described above, the semiconductor device 100 undergoes heat treatment in the manufacturing process, such as heating during soldering of each element, heating to cure the adhesive of the resin case 10 to the base plate 1, and heating to cure the sealing resin layer 15. As a result, the base plate 1 is generally curved downward in a trapezoidal shape due to the first to third points, and the shape of the top of the trapezoidal curve can be changed by adjusting the conditions of these heat treatments. The curvature shape of the base plate 1, which has a recess at its top, can be described as an "M-shape." By adjusting the heat treatment conditions, the height of the left and right peaks in this M-shape, the depth of the recess 72 in the M-shape, etc., can be changed. Since the heat treatment conditions for controlling the curvature of the base plate 1 are complex and involve many parameters that change the heat treatment conditions, they are determined by experiment, simulation, calculation, etc., according to the specifications of the semiconductor device 100. 【0071】 (Examples) Examples were carried out to confirm the effects of the present disclosure. In these examples, the semiconductor device 100 of the above-described embodiment was fabricated and attached to the cooling surface 51a of the heat dissipation substrate 51, which serves as a cooling mechanism, via a heat dissipation material 52. The heat dissipation substrate 51 was an iron plate. The heat dissipation material 52 was either silicone grease or a graphite sheet, and in this case, it was silicone grease. The heat dissipation material 52 was provided on the cooling surface 51a of the heat dissipation substrate 51. However, since the heat dissipation material 52 in this case is a layer of silicone grease, it will be basically ignored in the following description and will only be mentioned when necessary. The warpage of the base plate 1 before and after attachment to the cooling surface 51a was measured. The examples will now be described in detail. 【0072】Figure 6 shows how the semiconductor device 100 of the embodiment is attached to the cooling surface 51a of the heat dissipation substrate 51, which serves as a cooling mechanism. 【0073】 Referring to Figure 6, first, the warpage of the base plate 1 of the manufactured semiconductor device 100 was measured using a laser displacement sensor. This measurement was performed by irradiating the lower surface of the base plate 1 with the measurement laser light. 【0074】 Next, the base plate 1 was attached to the heat dissipation substrate 51 such that its lower surface 1a contacts the cooling surface 51a, which is the surface of the heat dissipation substrate 51 acting as a cooling mechanism, via the heat dissipation substrate 52. Specifically, bolts 61 were inserted through a pair of mounting holes 22 in the base plate 1, and the bolts 61 were first screwed into the bolt holes (not shown) of the heat dissipation substrate 51 with a force of 1.0 N·M (Newton-meter), thereby loosely fastening the base plate 1 to the heat dissipation substrate 51. Note that the heat dissipation material 52 in this case is a layer of silicone grease, so there are no bolt holes in the heat dissipation material 52. 【0075】 The warping of the base plate 1, which is loosely screwed to the heat dissipation substrate 51 in this manner, was measured by a laser displacement sensor. Specifically, the heat dissipation substrate 51 is provided with a narrow slit extending in a predetermined direction 23 in the mounting state of the semiconductor device 100 shown in Figure 6. The measurement laser beam from the laser displacement sensor is irradiated from the back surface of the heat dissipation substrate 51 through the slit and the layer of silicone grease onto the lower surface of the base plate 1 of the semiconductor device 100, thereby measuring the warping of the base plate 1. 【0076】 Next, the base plate 1 was further tightened to 4.7 N·m, thereby firmly screwing the base plate 1 to the heat dissipation substrate 51. 【0077】 Then, the warpage of the base plate 1, which is firmly screwed to the heat dissipation substrate 51, was measured by a laser displacement sensor. The measurement method was as described above. 【0078】Figure 7 is a graph showing measured data of the amount of warpage of the base plate 1 of the semiconductor device 100 before it is attached to the cooling surface 51a of the heat dissipation substrate 51, which serves as a heat dissipation substrate. In Figure 7, the horizontal axis represents the position X (mm) of the base plate 1 from a reference edge in a predetermined direction 23, and the vertical axis represents the amount of warpage Z (μm) of the base plate 1. The amount of warpage is expressed as the distance from the reference plane passing through the lower ends of both ends of the base plate 1 to the lower surface of the base plate 1. In Figure 7, the upward direction indicates the downward direction of the semiconductor device 100, and the amount of warpage in the downward direction of the semiconductor device 100 is represented by a positive (+) sign. 【0079】 Referring to Figure 7, the base plate 1 was curved in a predetermined direction 23, protruding downward in an M-shape. The amount of curvature was +80 μm. In this M-shaped curvature, there are two protrusions 71, 71 in the portion located below the two semiconductor chips 7, 7, and a recess 72 in the portion between these two protrusions, in other words, in the portion located below the space 31 between the two semiconductor chips 7, 7. 【0080】 Here, we will first describe a conventional example. Figure 9A is a conceptual graph showing the warping pattern 92 of the base plate of a conventional semiconductor device 90 before it is attached to the cooling surface 51a of the heat dissipation substrate 51 as a cooling mechanism. Figure 9B is a conceptual graph showing the warping pattern 92 of the base plate of a conventional semiconductor device 90 after it has been loosely fastened 91 to the cooling surface 51a of the heat dissipation substrate 51. Figure 9C is a conceptual graph showing the warping pattern 92 of the base plate of a conventional semiconductor device 90 after it has been firmly fastened 91 to the cooling surface 51a of the heat dissipation substrate 51. In Figures 9A to 9C, the horizontal axis represents the position X (mm) of the base plate 1 from the reference edge in the longitudinal direction (predetermined direction 23), and the vertical axis represents the amount of warping Z (μm) of the base plate 1. Furthermore, in Figures 9A to 9C, reference numeral 90 indicates a conventional semiconductor device, reference numeral 91 indicates a semiconductor chip, and reference numeral 92 indicates the curvature of the base plate 1. 【0081】 Referring to Figure 9A, the base plate of the conventional semiconductor device 90 before being attached to the cooling surface 51a of the heat dissipation substrate 51 is curved downward in a manner 92. 【0082】Referring to Figure 9B, the base plate of the conventional semiconductor device 90, which is loosely fastened to the cooling surface 51a of the heat dissipation substrate 51, bends in the opposite direction so as to create a bent portion 93 between both ends and the center, and bends in a manner 92 in which it has a substantially flat portion at both ends and a recess 94 in the center. 【0083】 Referring to Figure 9C, the base plate of the conventional semiconductor device 90, which is firmly fastened to the cooling surface 51a of the heat dissipation substrate 51, becomes even more severely warped when tightened more firmly than in the reverse-warped configuration 92 of Figure 9B, and the recess 94 expands accordingly. As a result, the portion located below the semiconductor chip 91 becomes part of the recess 94, the semiconductor chip 91 is separated from the cooling surface of the heat dissipation substrate 51, and the heat dissipation from the semiconductor chip 91 to the heat dissipation substrate 51 decreases. 【0084】 Next, an example will be described. Figure 8A is a graph showing the measured amount of warping of the base plate 1 of the semiconductor device 100, which is loosely fastened with bolts 61 to the cooling surface 51a of the heat dissipation substrate 51 as a cooling mechanism in the example. Figure 8B is a graph showing the measured amount of warping of the base plate 1 of the semiconductor device 100, which is firmly fastened with bolts 61 to the cooling surface 51a of the heat dissipation substrate 51 in the example. In Figures 8A and 8B, the horizontal axis represents the position X (mm) of the base plate 1 from the reference edge in a predetermined direction 23, and the vertical axis represents the amount of warping Z (μm) of the base plate 1. The amount of warping is expressed as the distance from the reference plane passing through the lower ends of both ends of the base plate 1 to the lower surface of the base plate 1. In Figures 8A and 8B, the upward direction indicates the downward direction of the semiconductor device 100, and the amount of warping of the semiconductor device 100 in the downward direction is represented by a positive (+) sign. 【0085】 Referring to Figure 8A, when the base plate 1 is loosely fastened to the cooling surface 51a of the heat dissipation substrate 51, both ends of the base plate 1 do not contact the cooling surface 51a of the heat dissipation substrate 51, and the higher of the two protrusions 71, 71 of the base plate 1 contacts the cooling surface 51a of the heat dissipation substrate 51. The recess 72 maintains almost the same state as before the base plate 1 was fastened to the cooling surface 51a of the heat dissipation substrate 51. Therefore, in this state, the base plate 1 as a whole is not warped in the opposite direction and can be said to be in a neutral state. 【0086】Referring to Figure 8B, when the base plate 1 is firmly fastened to the cooling surface 51a of the heat dissipation substrate 51, the base plate 1 bends in the reverse direction due to being tightened more strongly from the neutral state in Figure 8A. As a result, the two protrusions 71 are slightly separated from the cooling surface 51a of the heat dissipation substrate 51, and stepped portions 73 are formed at both ends of the base plate 1, while the recesses 72 become deeper. Comparing this reverse bending configuration with the reverse bending configuration of the conventional semiconductor device 90 in Figure 9C, in this reverse bending configuration, the protrusions 71, 71 are located below the semiconductor chips 7, 7 on the base plate 1. Therefore, the portion of the base plate 1 located below the semiconductor chips 7, 7 is closer to the cooling surface of the heat dissipation substrate 51, improving heat dissipation from the semiconductor chips 7, 7 to the heat dissipation substrate 51. 【0087】 As a result, it was confirmed that the semiconductor device 100 of the example makes it possible to improve heat dissipation from the semiconductor chips 7, 7 to the cooling mechanism. 【0088】 [Summary] As is clear from the above description, according to this embodiment 1, a semiconductor device 100 is provided in which an insulating substrate 5 on which semiconductor chips 7, 7 are arranged is arranged on a metal base plate 1 for heat conduction, and which is capable of improving heat dissipation from the semiconductor chips 7, 7 to the cooling mechanism. 【0089】 (Embodiment 2) Embodiment 2 of the present disclosure illustrates a configuration in which the semiconductor device comprises a transfer-type sealing resin as the sealing resin. 【0090】 Figure 10 is a longitudinal cross-sectional view of the semiconductor device 200 according to Embodiment 2. Referring to Figure 10, the semiconductor device 200 includes a transfer-type molded sealing resin body 18 as the sealing resin body 17. The other configurations are the same as those of the semiconductor device 100 of Embodiment 1. The differences will be explained below. 【0091】 [Configuration] The semiconductor device 200 of this second embodiment comprises a base plate 1, a main part 32 stacked on the base plate 1, and a molded sealing resin body 18 that covers the entire main part 32 and whose lower end is fixed to the base plate 1. 【0092】{Appearance} The appearance of the semiconductor device 200 is generally the same as that of the semiconductor device 100 in Figure 1, except that the resin case 10 in Figure 1 is replaced by the molded sealing resin body 18 in Figure 10 (however, the height is reduced by approximately half). {Manufacturing Method} The semiconductor device 200 includes the remaining elements of the semiconductor device 100 shown in Figure 2, excluding the resin case 10 and the sealing resin layer 15. In the manufacturing method of the semiconductor device 200, in the process shown in Figure 4C for the semiconductor device 100, instead of the resin case 10, the semi-finished product obtained in the process shown in Figure 4B is placed into a mold with an open bottom and an inner surface shape similar to that of the resin case 10, and the mold is sealed. Then, high-temperature, high-pressure epoxy resin is injected through an injection port provided in the appropriate place in the mold. After that, the epoxy resin is heated in the mold and solidified, and then the mold is removed to complete the semiconductor device 200 equipped with a transfer-type molded sealing resin body 18. The effects and benefits of the semiconductor device 200 manufactured in this manner are the same as those of the semiconductor device 100 in the embodiment. 【0093】 (Other Embodiments) In Embodiment 1 described above, the lower end of the resin case 10 may be fixed to the base plate 1 by means other than adhesive. For example, the lower end of the resin case 10 may be fixed to the base plate 1 by engagement, crimping, or the like. 【0094】 In Embodiment 1 described above, the sealing resin layer 15 may cover only a part of the main part 32, and in Embodiment 2 described above, the transfer-type sealing resin body 18 may cover only a part of the main part 32. 【0095】 From the above description, many improvements and other embodiments will be apparent to those skilled in the art. Therefore, the above description should be interpreted as illustrative only. 【0096】 The semiconductor device of the present invention is a semiconductor device in which an insulating substrate on which a semiconductor chip is arranged is arranged on a metal base plate for heat conduction, and is useful as a semiconductor device that can improve heat dissipation from the semiconductor chip to the cooling mechanism. 【0097】1 Base plate 2 First solder layer 3 Ceramic substrate 4a Bottom copper layer 4b Top copper layer 5 Insulating substrate 6 Second solder layer 7 Semiconductor chip 8 Third solder layer 9 Electrode member 10 Resin case 11 Power supply terminal 12 Pin member 13 Socket 14 Wiring member 15 Sealing resin layer 15a Gel-like resin body 15b Epoxy resin body 17 Sealing resin body 18 Transfer-type sealing resin body 21 Fixing space 22 Mounting hole 31 Space 41 Insulating substrate assembly 51 Heat dissipation base material 51a Cooling surface 61 Bolt 71 Protrusion 72 Recess 73 Step 100, 200 Semiconductor device

Claims

1. The device comprises a metal base plate for heat conduction, an insulating substrate having a lower copper layer and an upper copper layer formed on the lower and upper surfaces of a tough ceramic substrate, respectively, and soldered to the upper surface of the base plate at the lower copper layer by a first solder layer, two or three plate-shaped semiconductor chips soldered to the upper copper layer of the insulating substrate at the lower surface by a second solder layer, electrode members soldered to the upper surface of each of the two or three plate-shaped semiconductor chips at the lower surface by a third solder layer, and a sealing resin body stacked on the upper surface of the base plate, covering part or all of the first solder layer, the insulating substrate, the second solder layer, the two or three plate-shaped semiconductor chips, the third solder layer, and the electrode members, with its lower end fixed to the base plate, wherein the insulating substrate is fixed to the upper surface of the base plate, with a pair of fixing spaces between the base plate and both ends of the base plate in a predetermined direction for fixing the base plate to the cooling surface of the cooling mechanism. A semiconductor device in which the pair of fixed spaces and the two or three plate-shaped semiconductor chips are arranged in the predetermined direction, and the base plate is curved so as to have a convex portion that protrudes downward in the predetermined direction, with a convex portion located below each of the two or three plate-shaped semiconductor chips.

2. The semiconductor device according to claim 1, wherein the sealing resin body comprises a resin case whose lower end is fixed to the base plate so as to cover part or all of the first solder layer, the insulating substrate, the second solder layer, the two or three plate-shaped semiconductor chips, the third solder layer, and the electrode member, which are stacked on the upper surface of the base plate; and a sealing resin layer formed inside the resin case so as to cover part or all of the first solder layer, the insulating substrate, the second solder layer, the two or three plate-shaped semiconductor chips, the third solder layer, and the electrode member, which are stacked on the upper surface of the base plate.

3. The semiconductor device according to claim 1, wherein the sealing resin body is a molded sealing resin body that covers part or all of the first solder layer, the insulating substrate, the second solder layer, the two or three plate-shaped semiconductor chips, the third solder layer, and the electrode members stacked on the upper surface of the base plate, and whose lower end is fixed to the base plate.

4. The semiconductor device according to any one of claims 1 to 3, wherein the base plate has a shape that extends in the predetermined direction, and the lower end of the sealing resin body is fixed to the base plate such that it reaches both ends of the base plate.

5. The semiconductor device according to any one of claims 1 to 4, wherein the amount of warping of the base plate is on the order of μm.

6. The semiconductor device according to any one of claims 1 to 5, wherein the material of the base plate is copper or aluminum.

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