Power module, semiconductor device, and power conversion device

Abstract

A power module (1) has a package substrate (5), a sealing material (23) that seals a power semiconductor element (15) and the like, and a plurality of solder balls (21). The sealing material (23) includes a first part (25) that has a thickness (T1) that corresponds to a shorter height than the height (H) of the solder balls (21) from a first principal surface (7a) and a second part (27) that has a thickness (T2) that is greater than the thickness (T1). The solder balls (21) and the first part (25) of the sealing material (23) are formed on an outside edge side of the package substrate (5) with respect to the second part (27) of the sealing material (23).

Description

Power module, semiconductor device, and power conversion device

[0007]

[0001] The present disclosure relates to a power module, a semiconductor device, and a power conversion device.

[0002] There is a power module in which a power semiconductor element and an IC (Integrated Circuit) semiconductor element are encapsulated with a sealing material. The power module is provided with external terminals for electrically connecting to a mounting substrate. One form of the external terminals is an external terminal to which solder balls called BGA (Ball Grid Array) are applied (Patent Document 1, Patent Document 2, Patent Document 3).

[0003] The power semiconductor element and the like are mounted on a package substrate. On the surface of the insulating base material of the package substrate, a metal plate as a wiring is arranged. In the power module, in order to cope with a large current, a thicker metal plate is used as the metal plate for wiring. Also, in order to ensure electrical insulation, a thicker base material is used as the insulating base material. Further, a plurality of power semiconductor elements are mounted on one package substrate.

[0004] Therefore, compared with a general LSI (Large Scale Integrated Circuit) used in a personal computer or the like, the size and weight of the power module tend to be large. Also, the number of solder balls formed on the power module is overwhelmingly smaller than the number of solder balls formed on a general LSI.

[0005] Japanese Patent Application Laid-Open No. 7-193,162 Japanese Patent Application Laid-Open No. 11-297,876 Japanese Patent Application Laid-Open No. 2001-223,297

[0006] The power module is to be mounted on the mounting substrate by melting the solder balls. As described above, in the power module, the weight tends to be large and the number of solder balls is small. Therefore, when the solder balls are melted, the solder balls may be crushed, and there is a risk that the electrical connectivity and reliability between the power module and the mounting substrate may be impaired. <0(000014>This disclosure is made against such a backdrop, and one objective is to provide a power module that can suppress the crushing of solder balls when mounting the power module to a mounting board and improve electrical connection with the mounting board, another objective is to provide a semiconductor device to which such a power module is applied, and yet another objective is to provide a power conversion device to which the semiconductor device is applied.

[0008] The power module according to this disclosure is a power module mounted on a mounting substrate and comprises a package substrate, a semiconductor element, a encapsulant, and a plurality of external terminals. The package substrate includes a base material having a first main surface and a second main surface located opposite to the first main surface, with a first conductive plate formed on the first main surface and a second conductive plate formed on the second main surface. The semiconductor element is mounted on the first conductive plate. The encapsulant is formed to cover the first main surface of the package substrate and encapsulates the semiconductor element. The plurality of external terminals are formed on the first main surface of the package substrate and are electrically connected to the semiconductor element. The encapsulant comprises a first part and a second part. The first part has a first thickness corresponding to a height lower than the height of the external terminal from the first main surface, as a thickness from the first main surface. The second part encapsulates the semiconductor element and has a second thickness that is thicker than the first thickness, as a thickness from the first main surface. The plurality of external terminals and the first part of the encapsulant are arranged between the second part of the encapsulant and the outer edge of the package substrate.

[0009] The semiconductor device according to this disclosure is a semiconductor device in which the above-mentioned power module is mounted on a mounting substrate. The mounting substrate has either a recess or a through hole formed therein into which the second part of the encapsulating material is fitted. With the second part of the encapsulating material fitted into either the recess or the through hole, the power module is supported on the mounting substrate by the first part of the encapsulating material.

[0010] The power conversion device according to this disclosure comprises a main conversion circuit and a control circuit. The main conversion circuit has the above-mentioned semiconductor device and converts the input power and outputs it. The control circuit outputs a control signal to the main conversion circuit to control the main conversion circuit.

[0011] According to the power module described herein, when the power module is mounted on a mounting substrate, multiple external terminals melt, causing a first portion of the sealing material to come into contact with the mounting substrate, and the power module is supported by the first portion of the mounting substrate. This prevents the external terminals from being excessively crushed. As a result, the electrical connection between the power module and the mounting substrate can be improved, and the reliability of the electrical connection can be ensured.

[0012] According to the semiconductor device described herein, by applying the power module, the electrical connection between the power module and the mounting substrate can be improved, and the reliability of the electrical connection can be ensured.

[0013] According to the power conversion device described herein, by applying the above-mentioned semiconductor device, electrical connection reliability can be improved, and stable operation of the power conversion device can be achieved.

[0014] This is a plan view showing the structure of a power module according to Embodiment 1. This is a cross-sectional view taken along the cross-sectional line II-II shown in Figure 1 in the same embodiment. This is a cross-sectional view taken of a semiconductor device in which the power module is mounted on a mounting substrate in the same embodiment. This is a partially enlarged cross-sectional view taken of a power module according to one modified example in the same embodiment. This is a partially enlarged cross-sectional view taken of a power module according to one modified example in the same embodiment. This is a schematic plan view showing the structure of a power module according to another modified example in the same embodiment. This is a plan view showing the structure of a power module according to Embodiment 2. This is a cross-sectional view taken along the cross-sectional line VIII-VIII shown in Figure 7 in the same embodiment. This is a cross-sectional view taken of a semiconductor device in which the power module is mounted on a mounting substrate in the same embodiment. This is a partially enlarged cross-sectional view taken of a semiconductor device in which the power module is mounted on a mounting substrate in the same embodiment to explain the effects of the semiconductor device. This is a schematic plan view showing the structure of a power module according to one modified example in the same embodiment. This is a plan view showing the structure of a power module according to Embodiment 3. This is a cross-sectional view taken of a semiconductor device in which the power module is mounted on a mounting substrate in the same embodiment. This is a schematic plan view showing one step in the manufacturing method of a power module in the same embodiment to explain the effects of the power module. This is a schematic plan view illustrating a process performed after the process shown in Figure 14, for explaining the operation and effect of the power module in the same embodiment. This is a schematic plan view illustrating one step of a method for manufacturing a power module according to a modified example in the same embodiment. This is a cross-sectional view showing the structure of a power module according to Embodiment 4. This is a cross-sectional view showing the structure of a power module according to Embodiment 5. This is a cross-sectional view showing the structure of a power module according to Embodiment 6. This is a cross-sectional view showing the structure of a semiconductor device in which a power module is mounted on a mounting substrate according to Embodiment 7. This is a cross-sectional view showing the structure of a semiconductor device in which a power module is mounted on a mounting substrate according to Embodiment 8. This is a block diagram of a power converter according to Embodiment 9.

[0015] Embodiment 1. An example of a power module according to Embodiment 1 and an example of a semiconductor device to which the power module is applied will be described. For the sake of convenience of explanation, the X-Y Cartesian coordinate axes will be used as needed.

[0016] As shown in Figures 1 and 2, the power module 1 includes a package substrate 5, a power semiconductor element 15 and an IC semiconductor element 17, a sealing material 23, and a plurality of solder balls 21 as external terminals.

[0017] The package substrate 5 comprises a base material 7, a first metal plate 9 as a first conductive plate, and a second metal plate 11 as a second conductive plate. The base material 7 has a first main surface 7a and a second main surface 7b. The second main surface 7b is located on the opposite side from the first main surface 7a. The first metal plate 9 is formed to be in contact with the first main surface 7a of the base material 7. The second metal plate 11 is formed to be in contact with the second main surface 7b of the base material 7.

[0018] The first metal plate 9 is formed as a wiring pattern. The power semiconductor element 15 is mounted on one of the wiring patterns. The IC semiconductor element 17 is mounted on another of the wiring patterns. Each of the multiple solder balls 21 is formed on yet another wiring pattern.

[0019] The power semiconductor element 15 and a specific solder ball 21 are electrically connected by the first metal plate 9 and the bonding wire 19. The IC semiconductor element 17 and another specific solder ball 21 are electrically connected by the first metal plate 9. The power semiconductor element 15 and the IC semiconductor element 17 are electrically connected by the bonding wire 19.

[0020] The encapsulating material 23 is formed to cover the first main surface 7a of the base material 7. The encapsulating material 23 encapsulates the power semiconductor element 15, the IC semiconductor element 17, and the bonding wire 19. The shape of the encapsulating material 23 is a rectangle when viewed from the first main surface 7a side of the package substrate 5 (base material 7). Note that the term "rectangle" does not mean a geometrically precise rectangle, but rather includes, for example, manufacturing tolerances.

[0021] The sealing material 23 has a first end 24a, a second end 24b, a third end 24c, and a fourth end 24d. The first end 24a and the second end 24b are located at a distance apart in the X-axis direction and extend in the Y-axis direction. The third end 24c and the fourth end 24d are located at a distance apart in the Y-axis direction and extend in the X-axis direction.

[0022] The encapsulant 23 includes a first part 25 and a second part 27. The first part 25 has a thickness T1 from the first main surface 7a that corresponds to a height lower than the height H of the solder ball 21 from the first main surface 7a. The second part 27 has a thickness T2 from the first main surface 7a that is greater than the thickness T1. The power semiconductor element 15, etc., is substantially encapsulated by the second part 27. The first part 25 is formed at the first end 24a, the second end 24b, the third end 24c, and the fourth end 24d, respectively.

[0023] The first part 25 is formed to surround the second part 27 along its outer circumference in a plan view of the package substrate 5 (base material 7) as seen from the first main surface 7a side. That is, the first part 25 is formed along the portions corresponding to the four sides (first end 24a, second end 24b, third end 24c, and fourth end 24d) of the rectangular sealing material 23 in a plan view as seen from the first main surface 7a side.

[0024] Multiple solder balls 21 are arranged along the outer edge 6 of the package substrate 5. Multiple solder balls 21 are arranged along the first end 24a, second end 24b, third end 24c, and fourth end 24d of the encapsulating material 23, respectively. Multiple solder balls 21 and the first portion 25 of the encapsulating material 23 are formed on the outer edge 6 side of the package substrate 5 with respect to the second portion 27 of the encapsulating material 23. Multiple solder balls 21 are arranged on the outer edge 6 side of the package substrate 5 with respect to the first portion of the encapsulating material 23. The power module 1 according to Embodiment 1 is configured as described above.

[0025] Next, an example of a semiconductor device to which the power module 1 described above is applied will be explained. As shown in Figure 3, the semiconductor device 3 comprises the power module 1 and a mounting substrate 41. A recess 43 is formed on the main surface of the mounting substrate 41 facing the power module 1. The recess 43 has a depth D. The depth D is greater than the difference between the thickness T2 of the second part 27 and the thickness T1 of the first part 25.

[0026] The power module 1 is mounted on the mounting substrate 41 in such a manner that the second portion 27 of the encapsulating material 23 is fitted into a recess 43 of the mounting substrate 41. The power module 1 is supported on the mounting substrate 41 by the first portion 25 of the encapsulating material 23. In this case, a space (gap) is formed between the surface (upper surface) of the second portion 27 of the encapsulating material 23 and the bottom surface of the recess 43 formed in the mounting substrate 41.

[0027] According to the semiconductor device 3 described above, when the power module 1 is mounted on the mounting substrate 41, the solder balls 21 are melted while the second portion 27 of the encapsulating material 23 of the power module 1 is fitted into the recess 43 of the mounting substrate 41. When the solder balls 21 melt, the first portion 25 of the encapsulating material 23 comes into contact with the main surface 41a of the mounting substrate 41. In other words, the power module 1 is supported by the mounting substrate 41 by the first portion 25.

[0028] This prevents excessive crushing of the solder balls 21, even when the power module 1 is heavy and the number of solder balls 21 is small. As a result, the electrical connection between the power module 1 and the mounting board 41 can be improved, and the reliability of the electrical connection can be ensured.

[0029] The reason for using a mounting substrate 41 with recesses 43 is as follows: As described above, in order to prevent the solder balls 21 from being excessively crushed when mounting the power module 1 onto the mounting substrate 41, the power module 1 needs to be supported by the mounting substrate 41 by the sealing material 23.

[0030] Therefore, in the case of a mounting substrate in which the recess 43 is not formed, the power module 1 needs to be supported by the second part 27 of the sealing material 23. Moreover, in order to make an electrical connection between the solder ball 21 and the mounting substrate 41, the height H of the solder ball 21 needs to be greater than the thickness T2 of the second part 27.

[0031] The inventors evaluated the design and found that, considering the thickness T2 of the second part 27 in the sealing material 23, the solder ball 21 needed to be larger in size (height) than the largest commercially available solder ball (diameter). Therefore, from the standpoint of production cost, the second part 27 of the sealing material 23 was designed to fit into the recess 43 in order to use commercially available solder balls 21.

[0032] To fit the second part 27 into the recess 43, as shown in Figure 4, an inclined portion 26 may be provided on the second part 27 in the sealing material 23 of the power module 1. By providing an inclined portion 26 on the second part 27, the second part 27 can be easily fitted into the recess 43 of the mounting substrate 41. As shown in Figure 5, if the molten solder ball 21 solidifies before the first part 25 contacts the mounting substrate 41, a gap 51 may be created between the first part 25 and the mounting substrate 41.

[0033] Furthermore, in the power module 1 described above, the first part 25 was explained as being formed along the portions corresponding to the four sides of the rectangular sealing material 23 in a plan view from the first main surface 7a side. As long as the power module 1 has a structure that is stably supported on the mounting substrate 41, the first part 25 does not need to be formed along the portions corresponding to the four sides of the rectangular sealing material 23, but it is sufficient if it is formed along the portions corresponding to at least two sides.

[0034] For example, the first part 25 may be formed on each of the opposing first end 24a and second end 24b. Alternatively, the first part 25 may be formed on each of the opposing third end 24c and fourth end 24d. Furthermore, as shown in Figure 6, the first part 25 may be formed on each of the first end 24a and third end 24c.

[0035] Embodiment 2. An example of a power module according to Embodiment 2 and an example of a semiconductor device to which the power module is applied will be described. As shown in Figures 7 and 8, in the power module 1, a plurality of solder balls 21 are arranged along the first end 24a, second end 24b, third end 24c, and fourth end 24d of the sealing material 23, respectively. Each of the plurality of solder balls 21 is arranged with a gap between it and adjacent solder balls 21. The first portion 25 of the sealing material 23 is arranged in a plurality of portions such that it is located between adjacent solder balls 21 and other solder balls 21.

[0036] The first part 25 has a thickness T1 from the first main surface 7a that corresponds to a height lower than the height H of the solder ball 21 from the first main surface 7a. The second part 27 has a thickness T2 from the first main surface 7a that is greater than the thickness T1. Note that the other components are the same as those in the power module 1 shown in Figures 1 and 2, so the same reference numerals are used for the same components, and their descriptions will not be repeated unless necessary.

[0037] Next, an example of a semiconductor device to which the power module 1 described above is applied will be explained. As shown in Figure 9, the semiconductor device 3 comprises the power module 1 and a mounting substrate 41. A recess 43 is formed on the main surface of the mounting substrate 41 facing the power module 1. The recess 43 has a depth D. The depth D is greater than the thickness corresponding to the difference between the thickness T2 of the second part 27 and the thickness T1 of the first part 25.

[0038] The power module 1 is mounted on the mounting substrate 41 such that the second portion 27 of the encapsulating material 23 is fitted into the recess 43 of the mounting substrate 41. The power module 1 is supported on the mounting substrate 41 by the first portion 25 of the encapsulating material 23.

[0039] In the semiconductor device 3 described above, as in the case of the semiconductor device 3 described above, when the power module 1 is mounted on the mounting substrate 41, the solder ball 21 is melted with the second part 27 of the encapsulating material 23 of the power module 1 fitted into the recess 43 of the mounting substrate 41. When the solder ball 21 melts, the first part 25 of the encapsulating material 23 comes into contact with the main surface 41a of the mounting substrate 41, and the power module 1 is supported by the mounting substrate 41 by the first part 25.

[0040] This prevents excessive crushing of the solder balls 21, even when the power module 1 is heavy and the number of solder balls 21 is small. As a result, the electrical connection between the power module 1 and the mounting board 41 can be improved, and the reliability of the electrical connection can be ensured.

[0041] Furthermore, in the semiconductor device 3, the first part 25 is positioned between two adjacent solder balls 21. As a result, as shown in Figure 10, the insulation distance LB between one solder ball 21 and the other solder ball 21 can be made shorter than the insulation distance LA in the case where the first part 25 is not positioned. Consequently, this contributes to improving the electrical insulation of the semiconductor device 3. It also contributes to miniaturizing the power module 1.

[0042] In the above-described power module 1, the case where the first portion 25 is disposed between all of one solder ball 21 and another solder ball 21 adjacent to each other in a plan view seen from the first main surface 7a side has been described as an example. As the first portion 25, as long as the power module 1 has a structure that is stably supported on the mounting substrate 41, it is not necessary to be disposed between each of the solder balls 21, and at least three first portions 2 from the first end portion 24a side, and one first portion 25 may be disposed on the third end portion 24c side.

[0043] Embodiment 3. An example of a power module according to Embodiment 3 will be described. As shown in FIG. 12, in the power module 1, the plurality of solder balls 21 are disposed along each of the first end portion 24a and the second end portion 24b of the sealing material 23. On the other hand, the plurality of solder balls 21 are not disposed on the third end portion 24c side and the fourth end portion 24d side of the sealing material 23.

[0044] The sealing material 23 extends along the Y-axis direction to each of the corresponding outer edges 6 of the package substrate 5. The third end portion 24c of the sealing material 23 extends to the first outer edge 6a of the package substrate 5. The fourth end portion 24d of the sealing material 23 extends to the second outer edge 6b of the package substrate 5.

[0045] The first portion 25 in the sealing material 23 is formed along each of the first end portion 24a and the second end portion 24b that face each other among the first end portion 24a to the fourth end portion 24d of the rectangular sealing material 23 in a plan view seen from the first main surface 7a side of the package substrate 5 (base material 7). Regarding the other configurations, since they are the same as the configuration of the power module 1 shown in FIGS. 1 and 2, the same members are denoted by the same reference numerals, and the description thereof will not be repeated unless necessary.

[0046] Next, an example of a semiconductor device to which the above-described power module 1 is applied will be described. As shown in FIG. 13, in the semiconductor device 3, similar to the semiconductor device 3 shown in FIG. 3, the power module 1 is mounted on the mounting substrate 41 in such a manner that the second portion 27 of the encapsulant 23 is fitted into the recess 43 of the mounting substrate 41. The power module 1 is supported by the mounting substrate 41 by the first portion 25 of the encapsulant 23.

[0047] According to the above-described power module 1, similar to that described in the first embodiment, when the power module 1 is mounted on the mounting substrate 41, even if the solder balls 21 melt, the power module 1 is supported by the mounting substrate 41 by the first portion 25. As a result, the electrical connection between the power module 1 and the mounting substrate 41 can be made better, and the reliability of the electrical connection can be ensured.

[0048] Furthermore, in the above-described power module 1, the productivity can be improved by forming the encapsulant 23 by the transfer molding method using a large-area substrate. This will be described. First, as shown in FIG. 14, a package substrate 4 having a large area that will finally be singulated (package substrate 5) is prepared.

[0049] Here, one package substrate 5 to be singulated is defined as the first package substrate 5a. The package substrate 5 located in the positive Y-axis direction with respect to the first package substrate 5a is defined as the second package substrate 5b. The package substrate 5 located in the negative Y-axis direction with respect to the first package substrate 5a is defined as the third package substrate 5c. The package substrate 5 located in the positive X-axis direction with respect to the first package substrate 5a is defined as the fourth package substrate 5d. The package substrate 5 located in the negative X-axis direction with respect to the first package substrate 5a is defined as the fifth package substrate 5e.

[0050] Then, the package substrate 4 is enlarged in area in such a manner that the second package substrate 5b, the third package substrate 5c, the fourth package substrate 5d, and the fifth package substrate 5e are each connected to the first package substrate 5a.

[0051] The portion that will become the first outer edge 6a of the first package substrate 5a is connected to the portion that will become the second outer edge 6b of the second package substrate 5b. The portion that will become the second outer edge 6b of the first package substrate 5a is connected to the portion that will become the first outer edge 6a of the third package substrate 5c. The portion that will become the third outer edge 6c of the first package substrate 5a is connected to the portion that will become the fourth outer edge 6d of the fourth package substrate 5d. The portion that will become the fourth outer edge 6d of the first package substrate 5a is connected to the portion that will become the third outer edge 6c of the fifth package substrate 5e.

[0052] Next, power semiconductor elements 15 and IC semiconductor elements 17 are mounted on each region of the package substrate 4 that will be separated into individual pieces to form the package substrate 5. Next, the power semiconductor elements 15 and IC semiconductor elements 17 are electrically connected by bonding wires 19 (see Figure 15). Next, the power semiconductor elements 15 and IC semiconductor elements 17 are sealed with a sealing material 23. As shown in Figure 15, the package substrate 4 is placed inside the mold 61. The mold 61 is provided with an injection gate 63 into which a resin material 65, which will become the sealing material 23, is injected into the mold 61 (cavity).

[0053] Next, resin material 65 is injected from the injection gate 63 into the mold 61 (cavity) where the package substrate 4 is placed. At this time, as the resin material 65 is injected in the positive direction of the Y axis, the package substrate 5 located along the Y axis direction among the package substrate 5 that will be separated into individual pieces will be continuously sealed with the resin material 65. In addition, the portion corresponding to the first part 25 of the sealing material 23 will be molded along the Y axis direction.

[0054] After the resin material 65 has solidified, the package substrate 4 is removed from the mold 61. Solder balls are mounted on the package substrate 4. The package substrate 4 is then separated into individual package substrates 5 to complete the power module 1.

[0055] In the power module 1 described above, multiple solder balls 21 are arranged along the Y-axis and not along the X-axis. This allows a package substrate 4, in which individual package substrates 5 are arranged in a matrix, to be applied, and the package substrates 5 located along the Y-axis can be continuously sealed with resin material 65. As a result, multiple package substrates 5 can be manufactured efficiently, improving the productivity of the power module 1. Furthermore, production costs can be reduced.

[0056] In the power module 1 described above, the first portion 25 of the sealing material 23 was explained using the example of a case where it is formed along the opposing first end 24a and second end 24b of the rectangular sealing material 23, from the first end 24a to the fourth end 24d. In the power module 1, the first portion 25 may further be formed along the opposing third end 24c and fourth end 24d.

[0057] In this case, as shown in Figure 16, when sealing the package substrate 4 with the resin material 65, the portion of the mold 61 that forms the first portion 25 extending along the X-axis may become a flow resistance for the resin material 65 injected in the Y-axis direction. For this reason, it is desirable that the first portion 25 of the sealing material 23 be formed to extend only in the Y-axis direction.

[0058] Embodiment 4. An example of a power module and an example of a semiconductor device according to Embodiment 4 will be described. As shown in Figure 17, in the power module 1, the second metal plate 11 is formed as a single metal plate so as to be in contact with the entire surface of the second main surface 7b of the base material 7. In the semiconductor device 3 in which the power module 1 is mounted on a mounting substrate 41, the power module 1 is supported on the mounting substrate 41 by the first part 25 of the sealing material 23.

[0059] Furthermore, the configuration other than that is the same as that of the power module 1 shown in Figures 1 and 2, and the same as that of the semiconductor device 3 shown in Figure 3. For this reason, the same reference numerals are used for the same components, and their descriptions are not repeated unless necessary.

[0060] As described above, the semiconductor device 3 (power module 1) allows for better electrical connection between the power module 1 and the mounting substrate 41, as explained in Embodiment 1, and ensures the reliability of the electrical connection.

[0061] Furthermore, in the semiconductor device 3 described above, the second metal plate 11, which is a single metal plate, is formed so as to be in contact with the entire surface of the second main surface 7b of the substrate 7. This allows the heat generated from the power module 1 to be efficiently dissipated from the second metal plate 11, which is in contact with the entire surface of the second main surface. As a result, this can contribute to stabilizing the operation of the semiconductor device 3.

[0062] Embodiment 5. An example of a power module and an example of a semiconductor device according to Embodiment 5 will be described. As shown in Figure 18, in the power module 1, a base material 7 made of a high thermal conductivity insulating material 13 is used as the base material 7 in the package substrate 5. In the semiconductor device 3 in which the power module 1 is mounted on a mounting substrate 41, the power module 1 is supported on the mounting substrate 41 by the first part 25 of the encapsulating material 23.

[0063] Furthermore, the configuration other than that is the same as that of the power module 1 shown in Figures 1 and 2, and the same as that of the semiconductor device 3 shown in Figure 3. For this reason, the same reference numerals are used for the same components, and their descriptions are not repeated unless necessary.

[0064] As the base material 7 consisting of the high thermal conductivity insulating material 13 in the power module 1, for example, an organic substrate or a ceramic substrate can be used. The thermal conductivity of the organic substrate is, for example, 3 W / (m·K) or more, with an upper limit of approximately 20 W / (m·K). When a thermal conductivity of 20 W / (m·K) or more is required, a ceramic substrate is used. The upper limit of the thermal conductivity of the ceramic substrate is approximately 200 W / (m·K). Therefore, the thermal conductivity of the high thermal conductivity insulating material 13 is approximately 3 W / (m·K) or more and approximately 200 W / (m·K) or less.

[0065] As described in Embodiment 1, the semiconductor device 3 (power module 1) described above allows for better electrical connection between the power module 1 and the mounting substrate 41, thereby ensuring the reliability of the electrical connection. Furthermore, in the semiconductor device 3 described above, by applying a substrate 7 made of a high thermal conductivity insulating material 13 as the base material 7 in the package substrate 5, heat dissipation can be further improved.

[0066] Embodiment 6. An example of a power module and an example of a semiconductor device according to Embodiment 6 will be described. As shown in Figure 19, in the power module 1, a third metal plate 29, which is a third conductive plate, is arranged between the base material 7 and the second metal plate 11 in a manner that is in contact with the second metal plate 11. The third metal plate 29 is arranged so as to be fitted into the base material 7. The third metal plate 29 may be made of the same metal as the second metal plate 11, or it may be made of a different metal than the second metal plate 11.

[0067] Furthermore, the configuration other than that is the same as that of the power module 1 shown in Figures 1 and 2, and the same as that of the semiconductor device 3 shown in Figure 3. For this reason, the same reference numerals are used for the same components, and their descriptions are not repeated unless necessary.

[0068] As described in Embodiment 1, the semiconductor device 3 (power module 1) described above allows for better electrical connection between the power module 1 and the mounting substrate 41, thereby ensuring the reliability of the electrical connection. Furthermore, in the semiconductor device 3 described above, the third metal plate 29, which serves as a third conductive plate, is arranged between the substrate 7 and the second metal plate 11 in a manner that contacts the second metal plate 11. This further improves heat dissipation.

[0069] Embodiment 7. An example of a power module and an example of a semiconductor device according to Embodiment 7 will be described. As shown in Figure 20, in the semiconductor device 3, the power module 1 is mounted on a mounting substrate 41 in which a recess 43 is formed. A heat sink 31 is attached to the power module 1. As the heat sink 31, a first heat sink 31a is attached to a second metal plate 11. A thermal conductive material 33a is interposed between the first heat sink 31a and the second metal plate 11.

[0070] Furthermore, the configuration other than that is the same as that of the power module 1 shown in Figures 1 and 2, and the same as that of the semiconductor device 3 shown in Figure 3. For this reason, the same reference numerals are used for the same components, and their descriptions are not repeated unless necessary.

[0071] As described in Embodiment 1, the semiconductor device 3 (power module 1) described above allows for better electrical connection between the power module 1 and the mounting substrate 41, thereby ensuring the reliability of the electrical connection. Furthermore, in the semiconductor device 3 described above, the first heat sink 31a is attached to the second metal plate 11. This further improves heat dissipation.

[0072] Embodiment 8. An example of a power module and an example of a semiconductor device according to Embodiment 8 will be described. As shown in Figure 21, in the semiconductor device 3, the power module 1 is mounted on a mounting substrate 41 in which through holes 45 are formed. A heat sink 31 is attached to the power module 1. The heat sink 31 consists of a first heat sink 31a and a second heat sink 31b.

[0073] The first heat sink 31a is attached to the second metal plate 11. A thermal conductive material 33a is interposed between the first heat sink 31a and the second metal plate 11. The second heat sink 31b is attached to the sealing material 23. A thermal conductive material 33b is interposed between the second heat sink 31b and the sealing material 23.

[0074] Furthermore, the configuration other than that is the same as that of the power module 1 shown in Figures 1 and 2, and the same as that of the semiconductor device 3 shown in Figure 3. For this reason, the same reference numerals are used for the same components, and their descriptions are not repeated unless necessary.

[0075] As described in Embodiment 1, the semiconductor device 3 (power module 1) described above allows for better electrical connection between the power module 1 and the mounting substrate 41, thereby ensuring the reliability of the electrical connection. Furthermore, in the semiconductor device 3 described above, the first heat sink 31a is attached to the second metal plate 11, and the second heat sink 31b is attached to the sealing material 23. This further improves heat dissipation.

[0076] Embodiment 9. An example of a power conversion device to which the semiconductor device 3 according to Embodiment 9 is applied will be described. Here, a power conversion device to which the semiconductor device 3 described in any of Embodiments 1 to 8 described above is applied will be described. This disclosure is not limited to a specific power conversion device, but below, as Embodiment 9, a case in which this disclosure is applied to a three-phase inverter will be described.

[0077] Figure 22 is a block diagram showing the configuration of a power conversion system to which the power conversion device according to this embodiment is applied. The power conversion system shown in Figure 22 consists of a power supply 100, a power conversion device 200, and a load 300. The power supply 100 is a DC power supply and supplies DC power to the power conversion device 200. The power supply 100 can be made up of various things, for example, a DC grid, a solar cell, or a storage battery. It may also be made up of a rectifier circuit or AC / DC converter connected to an AC grid. Alternatively, the power supply 100 may be made up of a DC / DC converter that converts DC power output from a DC grid into a specific power.

[0078] The power converter 200 is a three-phase inverter connected between the power supply 100 and the load 300. It converts the DC power supplied from the power supply 100 into AC power and supplies the AC power to the load 300. As shown in Figure 22, the power converter 200 includes a main conversion circuit 201 that converts DC power into AC power and outputs it, and a control circuit 203 that outputs a control signal to the main conversion circuit 201 to control the main conversion circuit 201.

[0079] Load 300 is a three-phase motor driven by AC power supplied from power converter 200. Note that load 300 is not limited to a specific application; it is a motor mounted in various electrical devices, such as hybrid vehicles, electric vehicles, railway vehicles, elevators, or air conditioning equipment.

[0080] The details of the power converter 200 will be described below. The main conversion circuit 201 includes switching elements and freewheeling diodes (not shown). By switching the switching elements, the DC power supplied from the power supply 100 is converted into AC power and supplied to the load 300. There are various specific circuit configurations for the main conversion circuit 201, but the main conversion circuit 201 according to this embodiment is a two-level three-phase full-bridge circuit and can be composed of six switching elements and six freewheeling diodes antiparallel to each of the switching elements.

[0081] At least one of each switching element and each freewheeling diode in the main conversion circuit 201 is a switching element or freewheeling diode in a semiconductor device 202 corresponding to the semiconductor device 3 according to any of the embodiments 1 to 8 described above. The six switching elements form upper and lower arms connected in series for every two switching elements, and each upper and lower arm constitutes each phase (U phase, V phase, W phase) of a full bridge circuit. The output terminals of each upper and lower arm, i.e., the three output terminals of the main conversion circuit 201, are connected to the load 300.

[0082] Furthermore, the main conversion circuit 201 includes a drive circuit (not shown) for driving each switching element. The drive circuit may be built into the semiconductor device 202, or it may be configured to be a separate drive circuit from the semiconductor device 202. The drive circuit generates a drive signal to drive the switching elements of the main conversion circuit 201 and supplies it to the control electrodes of the switching elements of the main conversion circuit 201. Specifically, according to a control signal from the control circuit 203, which will be described later, it outputs a drive signal to turn on the switching element and a drive signal to turn off the switching element to the control electrodes of each switching element. When the switching element is kept in the ON state, the drive signal is a voltage signal (ON signal) that is greater than or equal to the threshold voltage of the switching element, and when the switching element is kept in the OFF state, the drive signal is a voltage signal (OFF signal) that is less than or equal to the threshold voltage of the switching element.

[0083] The control circuit 203 controls the switching elements of the main converter circuit 201 so that the desired power is supplied to the load 300. Specifically, it calculates the time (on time) that each switching element of the main converter circuit 201 should be in the ON state based on the power to be supplied to the load 300. For example, the main converter circuit 201 can be controlled by PWM control, which modulates the on time of the switching elements according to the voltage to be output. The control circuit then outputs a control command (control signal) to the drive circuit of the main converter circuit 201 so that an ON signal is output to the switching elements that should be in the ON state at each point in time, and an OFF signal is output to the switching elements that should be in the OFF state. The drive circuit outputs an ON signal or an OFF signal as a drive signal to the control electrode of each switching element according to this control signal.

[0084] In the power conversion device according to this embodiment, since the semiconductor device 3 according to any of embodiments 1 to 8 is used as the semiconductor device 202 constituting the main conversion circuit 201, the reliability of the electrical connection is improved, and stable operation of the power conversion device can be achieved.

[0085] In this embodiment, an example of applying the present disclosure to a two-level three-phase inverter has been described, but the present disclosure is not limited to this and can be applied to various power conversion devices. In this embodiment, a two-level power conversion device is used, but a three-level or multi-level power conversion device may also be used, and in the case of supplying power to a single-phase load, the present disclosure may be applied to a single-phase inverter. Furthermore, in the case of supplying power to a DC load, etc., the present disclosure can also be applied to a DC / DC converter or an AC / DC converter.

[0086] Furthermore, the power conversion device to which this disclosure is applied is not limited to cases where the load is an electric motor, but can also be used, for example, as a power supply device for an electrical discharge machine, laser processing machine, induction heating cooker, or contactless power supply system, and can even be used as a power conditioner for a solar power generation system or energy storage system.

[0087] Furthermore, the semiconductor devices described in each embodiment can be combined in various ways as needed.

[0088] The embodiments disclosed herein are illustrative and not limiting. This disclosure is indicated by the claims, not the scope described above, and all modifications in the meaning and scope equivalent to the claims are intended.

[0089] This disclosure is effectively utilized in power modules in which power semiconductor elements are sealed with an encapsulating material, and in semiconductor devices such as those in which the power module is mounted on a substrate.

[0090] 1 Power module, 3 Semiconductor device, 4 Package substrate, 5 Package substrate, 5a First package substrate, 5c Second package substrate, 5d Third package substrate, 5e Fourth package substrate, 5f Fifth package substrate, 6 Outer edge, 6a First outer edge, 6b Second outer edge, 6c Third outer edge, 6d Fourth outer edge, 7 Base material, 7a First main surface, 7b Second main surface, 9 First metal plate, 11 Second metal plate, 13 High thermal conductivity insulating material, 15 Power semiconductor element, 17 IC semiconductor element, 19 Bonding wire, 21 Solder ball, 23 Encapsulating material, 24a First end, 24b Second end, 24c Third end, 24d Fourth end, 25 First part, 26 Inclined part, 27 Second part, 29 Metal plate, 31 Heat sink, 31a First heat sink, 31b Second heat sink, 33a, 33b Thermal conductive material, 41 Mounting substrate, 41a Main surface, 43 Recess, 45 Through hole, 51 Gap, 61 Mold, 63 Resin gate, 65 Resin material, H Height, T1, T2 Thickness, D Depth, LA, LB Distance, 100 Power supply, 200 Power converter, 201 Main converter circuit, 202 Semiconductor device, 203 Control circuit, 300 Load.

Claims

1. A power module mounted on a mounting substrate, comprising: a package substrate having a first main surface and a second main surface located opposite to the first main surface, wherein a first conductive plate is formed on the first main surface and a second conductive plate is formed on the second main surface; a semiconductor element mounted on the first conductive plate; a sealing material formed to cover the first main surface of the package substrate and sealing the semiconductor element; and a plurality of external terminals formed on the first main surface of the package substrate and electrically connected to the semiconductor element, wherein the sealing material comprises: a first part having a first thickness corresponding to a height lower than the height of the external terminals from the first main surface as the thickness from the first main surface; and a second part sealing the semiconductor element and having a second thickness greater than the first thickness as the thickness from the first main surface; and the plurality of external terminals and the first part of the sealing material are arranged between the second part of the sealing material and the outer edge of the package substrate.

2. The power module according to claim 1, wherein the first portion of the sealing material is formed along the outer circumference of the second portion of the sealing material, and the plurality of external terminals are arranged between the first portion and the outer edge of the package substrate.

3. The power module according to claim 2, wherein the shape of the sealing material is rectangular in a plan view of the package substrate viewed from the first main surface side, and the first part is formed along portions corresponding to at least two sides of the rectangular sealing material.

4. The power module according to claim 3, wherein the first part is formed along the portions corresponding to the two sides of the sealing material, which are opposite to each other, the first side and the second side.

5. The power module according to claim 4, wherein the plurality of external terminals are arranged along portions corresponding to each of the first and second sides facing each other, and portions of the sealing material corresponding to each of the other third and fourth sides facing each other are located at the outer edge of the package substrate.

6. The power module according to claim 1, wherein each of the plurality of external terminals is spaced apart from one another, and the first portion of the sealing material is arranged in a manner such that it is positioned between one adjacent external terminal and another external terminal.

7. The power module according to claim 6, wherein the plurality of first parts in the sealing material are arranged at different positions from each other in a manner that they are not aligned in a straight line.

8. The power module according to any one of claims 1 to 7, wherein the second conductive plate is formed to be in contact with the entire surface of the second main surface of the substrate.

9. The power module according to any one of claims 1 to 8, wherein the base material is formed from a thermally conductive insulating material.

10. The power module according to claim 9, wherein the thermal conductivity of the substrate is 3 W / (m·K) or more and 200 W / (m·K) or less.

11. The power module according to any one of claims 1 to 7, wherein the package substrate includes a third conductive plate positioned between the substrate and the second conductive plate, in a manner that the package substrate is fitted into the substrate and in contact with the second conductive plate.

12. A semiconductor device comprising a power module according to any one of claims 1 to 11 mounted on a mounting substrate, wherein the mounting substrate has either a recess or a through hole into which the second portion of the sealing material is fitted, and the power module is supported on the mounting substrate by the first portion of the sealing material with the second portion of the sealing material fitted into either the recess or the through hole.

13. The semiconductor device according to claim 12, wherein the first heat sink is bonded to the second conductive plate.

14. The semiconductor device according to claim 12 or 13, wherein the mounting substrate has the through hole formed therein, and the second part of the sealing material is fitted into the through hole, and the second heat sink is bonded to the second part that is exposed from the through hole.

15. A power conversion device having a semiconductor device according to any one of claims 12 to 14, comprising a main conversion circuit that converts and outputs input power, and a control circuit that outputs a control signal to the main conversion circuit for controlling the main conversion circuit.

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