Semiconductor module

Abstract

The present application provides a semiconductor module having a power semiconductor chip, which is small in deviation of a bonding position of a resin case bonded to a substrate and high in assembly quality and reliability of stress of a bonding portion of the case and the substrate. The semiconductor module has a substrate, an insulating substrate joined to the substrate, a semiconductor chip joined to the insulating substrate, and a case bonded to the substrate by an adhesive material, characterized in that the substrate is composed of a first material in a plate shape and a second material covering the first material and having a larger linear expansion coefficient than that of the first material, the second material has a first region disposed at a corner portion of the substrate and a second region disposed at a peripheral portion of the substrate and having a narrower width than that of the first region in a plan view of the substrate, the case covers at least a part of a side surface of the substrate, is bonded to the substrate by the adhesive material at least on an upper surface of the substrate, and has a larger linear expansion coefficient than that of the first material, a length from a center of an edge of the substrate to an end portion of the substrate is set as L1, a length from the center of the edge of the substrate to a boundary between the first region and the second region is set as L2, L1-L2 is thicker than a plate thickness of the substrate, a length from the center of the edge of the substrate to an end portion of the corner portion of the substrate on the side surface of the substrate, at which the adhesive material bonds the substrate and the case, is set as L3, and when the side surface of the substrate has no adhesive material, L3 is set as 0, L3≥L2 or L2-L3≥L1-L2 is satisfied.

Description

Technical Field

[0001] This invention relates to the construction of a semiconductor module, and more particularly to a technique for mounting a semiconductor module having power semiconductor chips such as IGBTs. Background Technology

[0002] In recent years, the demand for semiconductor modules with power semiconductor chips such as IGBTs (Insulated Gate Bipolar Transistors) has been expanding as power control devices installed in power generation systems such as wind power generation, railways, and electric vehicles and hybrid vehicles. The development of module structures that can suppress manufacturing deviations and ensure product quality has become increasingly important.

[0003] On the other hand, semiconductor modules with power semiconductor chips such as IGBTs experience heat rises and falls depending on the operating conditions. Due to these heat rises and falls, the internal structure and mounting structure of the semiconductor module are subjected to thermal shock, leading to accelerated fatigue and deterioration.

[0004] Therefore, as one of the reliability evaluation tests for semiconductor modules, a power cycling test (temperature cycling test) is conducted. This power cycling test evaluates the module's resistance to changes in electrical and thermal shock caused by repeated ON / OFF cycles.

[0005] In power cycling tests (temperature cycling tests), a large electrical current is applied to a power semiconductor chip, repeatedly subjecting the chip to self-heating and cooling, thereby evaluating the thermal stress resistance of components with different coefficients of linear expansion. It is used to evaluate the bonding reliability at the interfaces of various components such as the chip, substrate, solder, and bonding wires, as well as the strain and crack durability of the chip and encapsulation resin.

[0006] As background technology in this field, there is, for example, the technology in Patent Document 1. Patent Document 1 describes a method that, "By making the wall thickness t1 of the resin portion on the side of the housing parallel to the long side direction L2 thicker than the wall thickness t2 of the resin portion on the side parallel to the short side direction L1 of the module (L1 < L2, t1 > t2), deformation of the module is suppressed, the precision of the component is improved, and the bonding area between the resin housing 108 and the bottom metal substrate 205 is ensured, preventing defects such as peeling of the resin housing 108 from the bottom metal substrate 205 caused by temperature cycling." (Patent Document 1, paragraph 0032, etc.)

[0007] Furthermore, Patent Document 2 describes a "container-shaped frame 10 consisting of a substrate 1 and a housing 9 for housing an insulating substrate 3 and a semiconductor chip 5, wherein the housing 9 has a greater thickness in the Z direction than the aforementioned bonding structure in order to accommodate the bonding structure of the substrate 1, the insulating substrate 3, and the semiconductor chip 5." (Patent Document 2, paragraph 0015, etc.)

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2002-164503

[0011] Patent Document 2: Japanese Patent Application Publication No. 2018-10989 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] Furthermore, as described above, in current semiconductor modules with power semiconductor chips, the mainstream mounting structure is that a ceramic insulating substrate carrying power semiconductor chips such as IGBTs is bonded to the substrate by substrate bonding solder, and a resin housing is fixed to the upper surface of the substrate by adhesive material and fixing screws.

[0014] A resin casing surrounds the power semiconductor chip and the insulating substrate, and the interior of the casing is filled with silicone gel as a sealing material.

[0015] The substrate uses metallic materials such as copper (Cu) and silicon carbide particle-reinforced aluminum composite (AlSiC).

[0016] AlSiC has a coefficient of linear expansion that is as small as that of ceramic insulating substrates, making it a material that can reduce the load on the solder used for bonding substrates. It also has excellent thermal conductivity, so it is often used as a substrate material for semiconductor modules with power semiconductor chips.

[0017] When AlSiC is used as the substrate material, an aluminum (Al) film is typically applied to the upper and side surfaces of the AlSiC base material. The Al film covering the AlSiC is used to ensure the processability of the substrate and the wettability of the solder.

[0018] However, the coefficient of linear expansion of Al and resin is greater than that of AlSiC. Therefore, it is known that stress is generated during temperature changes such as power cycling tests (temperature cycling tests). Depending on the bonding condition, such as the deviation of the bonding position of the resin shell bonded to the substrate, cracks may occur in the Al film covering AlSiC and the AlSiC as the base material.

[0019] Neither Patent Document 1 nor Patent Document 2 mentions the problem of temperature-induced cracking at AlSiC substrates or its solutions.

[0020] Therefore, the object of the present invention is to provide a semiconductor module with a power semiconductor chip, which has a small deviation in the bonding position of the resin housing bonded to the substrate, and can reduce the stress at the bonding part between the housing and the substrate, resulting in a semiconductor module with high assembly quality and reliability.

[0021] Solution for solving the problem

[0022] To address the aforementioned issues, the present invention provides a semiconductor module comprising: a substrate; an insulating substrate bonded to the substrate; a semiconductor chip bonded to the insulating substrate; and a housing bonded to the substrate by an adhesive material. The semiconductor module is characterized in that the substrate is composed of a plate-like first material and a second material covering the first material and having a coefficient of linear expansion greater than that of the first material. Viewed from above, the second material has: a first region disposed at a corner of the substrate; and a second region disposed at the outer periphery of the substrate and having a width narrower than that of the first region. The housing covers at least a portion of the side surface of the substrate, at least on the substrate... The upper surface is bonded to the substrate by the adhesive material, and the linear expansion coefficient of the shell is greater than that of the first material. When the length from the center of the edge of the substrate to the end of the substrate is set as L1, and the length from the center of the edge of the substrate to the boundary between the first region and the second region is set as L2, L1-L2 is thicker than the substrate. When the length from the center of the edge of the substrate to the end of the corner side of the substrate on the side of the substrate where the adhesive material of the substrate and the shell is bonded is set as L3, and when there is no adhesive material on the side of the substrate, when L3 = 0, L3 ≥ L2 or L2-L3 ≥ L1-L2 is satisfied.

[0023] Invention Effects

[0024] According to the present invention, a semiconductor module with a power semiconductor chip can be realized, which has high assembly quality and high reliability, and has a small deviation in the bonding position of the resin housing bonded to the substrate and can reduce the stress at the bonding part between the housing and the substrate.

[0025] Other issues, structures, and effects not mentioned above become clear through the following description of implementation methods. Attached Figure Description

[0026] Figure 1 This is a bottom view of a semiconductor module shown as a comparative example of the present invention.

[0027] Figure 2 yes Figure 1 A-A' sectional view.

[0028] Figure 3 It is a conceptual representation Figure 1 A diagram showing the stress on the side surface of the substrate of a semiconductor module.

[0029] Figure 4 This is a bottom view of the semiconductor module of Embodiment 1 of the present invention.

[0030] Figure 5 yes Figure 4 The B-B' sectional view.

[0031] Figure 6 This is a bottom view of the semiconductor module of Embodiment 2 of the present invention.

[0032] Figure 7 yes Figure 6 The C-C' sectional view.

[0033] Figure 8 It means Figure 6 A graph showing the relationship between the bonding area of ​​a semiconductor module and the stress generated (GS).

[0034] Figure 9 It means Figure 6 A diagram of a variation.

[0035] Figure 10 This is a bottom view of the semiconductor module of Embodiment 3 of the present invention.

[0036] Figure 11 This is a bottom view of the semiconductor module of Embodiment 4 of the present invention.

[0037] Figure 12 yes Figure 11 The D-D' section view. Detailed Implementation

[0038] Hereinafter, embodiments of the present invention will be described using the accompanying drawings. Furthermore, in the drawings, the same structures are labeled with the same symbols, and detailed descriptions of repeated parts are omitted.

[0039] Example 1

[0040] First, refer to Figures 1 to 3 The basic structure of the semiconductor module, which is the subject of this invention, and its problems will be described. Figure 1 This is a bottom view of a semiconductor module shown as a comparative example of the present invention. Figure 2 yes Figure 1 A-A' sectional view. Figure 3It is a conceptual representation in Figure 1 A diagram showing the stress generated on the substrate side of a semiconductor module.

[0041] Furthermore, details regarding the various components of the semiconductor module are described in detail in the description of embodiments of the present invention. Additionally, the structures described herein, except for those relevant to the subject matter, are common to all embodiments of the present invention. Structures different from those described herein are described in each embodiment.

[0042] like Figure 1 and Figure 2 As shown, in semiconductor module 1, a ceramic insulating substrate 22, on which a circuit wiring pattern 20 and a lower surface conductor layer 21 are formed, is bonded to a plate-shaped substrate 2 made of metal materials such as copper (Cu) and silicon carbide particle reinforced aluminum composite (AlSiC) by a substrate bonding solder 24. A semiconductor chip 23 is bonded to the circuit wiring pattern 20 by a chip bonding solder 25.

[0043] In addition, although not shown, semiconductor module 1 is equipped with terminals and metal wires for external electrical connection.

[0044] On the upper surface of the substrate 2, a housing 7 made of resin such as PBT (Polybutylene Terephtalate) or PPS (Polyphenylene Sulfide) is fixed by adhesive material 8 and fixing screws 6. The substrate 2 has fixing holes 5 for fixing the semiconductor module 1 to heat dissipation fins (not shown). The housing 7 surrounds the insulating substrate 22 on which the semiconductor chip 23 is mounted, and the interior of the housing 7 is filled with silicone gel 26. Furthermore, a resin cap 27 is provided on the upper surface of the housing 7. The semiconductor chip 23 is protected by the sealing of the silicone gel 26 and the cap 27.

[0045] Here, if the bonding position of the housing 7 relative to the substrate 2 shifts, there is a possibility of incomplete sealing of the silicone gel 26. Therefore, ensuring the bonding positioning accuracy of the housing 7 is important. Therefore, housing protrusions 12 are provided on the lower surface of the four sides of the housing 7. During the bonding process of the housing 7 to the substrate 2, these housing protrusions 12 are positioned opposite to the side surfaces of the four sides of the substrate 2 to ensure the bonding positioning accuracy of the housing 7. Therefore, as... Figure 2 As shown, the housing 7 is bonded to the upper surface and side surface of the substrate 2 via the upper surface portion 9 and the side surface portion 10 of the adhesive material 8.

[0046] The problem to be solved by the present invention will be described in detail using the comparative examples described above.

[0047] Assuming the substrate 2 is made of silicon carbide particle-reinforced aluminum composite material (AlSiC). For example... Figure 1 and Figure 2 As shown, the substrate 2 is composed of two materials: AlSiC material 3 and Al material 4 covering the upper surface and sides of AlSiC material 3.

[0048] AlSiC has a coefficient of linear expansion that is as small as that of the insulating substrate 22, thus reducing the load on the solder 24 used for substrate bonding. Furthermore, due to its excellent thermal conductivity, it is frequently used as a substrate material for semiconductor modules containing power semiconductor chips. The Al material 4 covering the AlSiC material 3 is used to ensure the processability of the substrate 2 and the wettability of the solder. Additionally, the coefficient of linear expansion of Al material 4 is greater than that of AlSiC material 3.

[0049] Here, the inventors of this application have discovered that when the adhesive end 13 of the housing 7 and the side of the substrate 2 is located near the narrower region 16 side of the boundary 14 where the y-direction dimension of the Al material 4 changes from a wider region 15 to a narrower region 16, the stress generated on the side of the substrate 2 may increase when the temperature of the semiconductor module 1 changes from a high temperature to a low temperature.

[0050] Figure 3 A schematic diagram illustrating the mechanism of stress increase is shown. Considering symmetry, a quarter-scale model of semiconductor module 1 is shown. Focusing on, for example, the long side (either the long or short side), as the temperature of semiconductor module 1 changes from high to low, the Al material 4, with its larger coefficient of linear expansion, contracts in the wider region (first region) 15 where the width of Al material 4 increases (in the case of the long side, the length in the y-direction), as indicated by the arrows in the diagram. Additionally, the shell 7, which is bonded to the side of substrate 2 and also has a large coefficient of linear expansion, also contracts. It can be assumed that due to the contraction of both components, the stress in the x-direction generated on the surface of the Al material at the bonding end 13, i.e., the narrow region (second region) 16 of Al material 4, increases.

[0051] To verify this mechanism, thermal stress analysis was performed on a semiconductor module. The analytical model adopted... Figure 3 The 1 / 4 scale model shown was subjected to temperature conditions ranging from a high temperature of 125°C to a low temperature of -40°C. Analysis was performed on both cases where there was adhesion between the side of the substrate 2 and the shell 7, and the stress generated by the Al material covering the side of the substrate 2 was compared and evaluated. The location of the adhesive end 13 was set as... Figure 3 The example shown illustrates the case where the distance x1 is 1 mm.

[0052] As a result, it can be confirmed that, in the case of side bonding, the stress generated in the Al material reaches its maximum value at the bonded end 13. Furthermore, it can be confirmed that the maximum stress value in the case of side bonding increases by approximately 1.4 times compared to the case without side bonding. Based on the results of this analysis, it can be considered that... Figure 3 The mechanism of stress increase shown is appropriate.

[0053] Therefore, it can be seen that stress is generated during temperature changes such as power cycling tests (temperature cycling tests), and depending on the bonding state such as the deviation of the bonding position of the resin shell 7 bonded to the substrate 2, cracks may be generated in the Al material 4 covering the AlSiC material 3 due to the increase in stress.

[0054] Next, refer to Figure 4 as well as Figure 5 The semiconductor module of Embodiment 1 of the present invention will be described below. Figure 4 This is a bottom view of the semiconductor module in this embodiment. Figure 5 yes Figure 4 The B-B' sectional view. Figure 4 as well as Figure 5 These are respectively equivalent to the comparative examples mentioned above. Figure 1 as well as Figure 2 .

[0055] like Figure 4 and Figure 5 As shown, in the semiconductor module 1 of this embodiment, a ceramic insulating substrate 22 having a circuit wiring pattern 20 and a lower surface conductor layer 21 formed thereon is bonded to a plate-shaped substrate 2 made of AlSiC material 3 and Al material 4 by a substrate bonding solder 24, and a semiconductor chip 23 is bonded to the circuit wiring pattern 20 by a chip bonding solder 25.

[0056] In addition, although not shown, semiconductor module 1 is equipped with terminals and metal wires for external electrical connection.

[0057] A housing 7 made of resin such as PBT or PPS is fixed to the upper surface of the substrate 2 using adhesive material 8 and fixing screws 6. The substrate 2 has fixing holes 5 for fixing the semiconductor module 1 to heat dissipation fins (not shown). The housing 7 surrounds the insulating substrate 22 on which the semiconductor chip 23 is mounted, and the interior of the housing 7 is filled with silicone gel 26. Furthermore, a resin cap 27 is provided on the upper surface of the housing 7. The semiconductor chip 23 is protected by the sealing of the silicone gel 26 and the cap 27.

[0058] Housing protrusions 12 are provided on the lower surface of the four sides of the housing 7. The housing protrusions 12 face the sides of the base 2 and are configured to cover at least a portion of the sides of the base 2. This is to ensure the bonding positioning accuracy of the housing 7 by providing the housing protrusions 12 facing the sides of the base 2 during the bonding process of the housing 7 to the base 2. Figure 5 As shown, the housing 7 is bonded to the upper surface and side surface of the substrate 2 via the upper surface portion 9 and the side surface portion 10 of the adhesive material 8.

[0059] The substrate 2 will be described in detail. For example... Figure 4 and Figure 5 As shown, the substrate 2 is composed of two materials: AlSiC material 3 and Al material 4 covering at least the upper surface and sides of the AlSiC material 3. Since the coefficient of linear expansion of AlSiC is as small as that of the insulating substrate 22, it is a material that can reduce the load on the solder 24 used for substrate bonding. Furthermore, due to its excellent thermal conductivity, it is frequently used as a substrate material for semiconductor modules containing power semiconductor chips.

[0060] The Al film covering AlSiC is used to ensure the substrate's processability and solder wettability. Additionally, Al has a greater coefficient of linear expansion than AlSiC.

[0061] If we focus on the long side, or for example the long side, when viewing the substrate 2 from above, the Al material 4 consists of a wider region (first region) 15 of Al material 4 located at the corner of the substrate 2 and a narrower region (second region) 16 of Al material 4 located on the outer periphery of the substrate 2, the width of which (the length in the y-direction when viewing the long side) is narrower than the wider region (first region) 15 of Al material 4. At the corner of the substrate 2, since it is necessary to machine fixing holes 5 for fixing the substrate 2 to the heat dissipation fins (not shown) and holes for fixing the housing 7 by fixing screws 6, Al material 4, being a material with excellent machinability, is used.

[0062] Next, the bonding area between the side of the substrate 2 and the housing 7 will be described in detail. The housing 7 covers at least a portion of the side of the substrate 2 and is bonded to the substrate 2 at least on the upper surface of the substrate 2 via adhesive material 8.

[0063] In the semiconductor module 1 of this embodiment, as Figure 4As shown, the position of the bonding end 13 of the base 2 and the housing 7 is defined by the length (L1) from the center of the edge of the base 2 to the end of the base 2, the length (L2) from the center of the edge of the base 2 to the boundary between the first region 15 and the second region 16, the length (L3) from the center of the edge of the base 2 to the end of the adhesive material 8 (more specifically, the adhesive material side portion 10) on the side of the base 2 that bonds the base 2 and the housing 7, and the thickness of the base 2.

[0064] In this embodiment, the wider region (first region) 15 of Al material 4 is set such that the difference between L1 and L2 (L1-L2), i.e., the length in the x-direction of the wider region (first region) 15 of Al material 4 is greater than the thickness of the substrate 2. Furthermore, the position of the adhesive end 13 is defined such that L3 is greater than or equal to L2 (L3≥L2).

[0065] Here, as described above, we consider the case where the temperature of the semiconductor module 1 changes from a high temperature to a low temperature. When the temperature of the semiconductor module 1 changes from a high temperature to a low temperature, the housing 7, which has a large coefficient of linear expansion and is bonded to the side of the substrate 2, shrinks in the x-direction. However, since the bonding end 13 is located in a wider region (first region) 15 of the Al material 4, the width of the Al material 4 (the length in the y-direction when considering the long side) is wider and its rigidity is greater. Therefore, the deformation of the Al material 4 at the bonding end 13 caused by the shrinkage of the housing 7 is smaller, and the resulting stress is also suppressed.

[0066] To confirm this effect, a thermal stress analysis was performed on the semiconductor module 1 of this embodiment, similar to the study in the comparative example described above. The analytical model, load conditions, etc., were the same as in the comparative example, and the position of the adhesive end 13 was set to L3-L2 = 1 mm.

[0067] As a result, the maximum stress value with side bonding is approximately the same as that without side bonding. Therefore, in this embodiment where the condition L3≥L2 is satisfied, the stress generated on the substrate 2 (AlSiC material 3 and Al material 4) can be suppressed at the bonding end 13, improving structural reliability.

[0068] Furthermore, in this embodiment, the long side of semiconductor module 1 ( Figure 4 The bonding area (on the x-direction side) is the focus, and the dimensional relationship and effect of the substrate 2, housing 7, and bonding portion are explained. However, on the short side of the semiconductor module 1 (… Figure 4 The same dimensional relationship and its effect also hold true for the y-direction side.

[0069] Example 2

[0070] Reference Figures 6 to 9The semiconductor module of Embodiment 2 of the present invention will be described below. Figure 6 This is a bottom view of the semiconductor module in this embodiment. Figure 7 yes Figure 6 The C-C' sectional view. Figure 6 and Figure 7 Each is equivalent to Example 1 Figure 4 and Figure 5 . Figure 8 It means Figure 6 A graph showing the relationship between the bonding area and the stress (GS) generated in the semiconductor module. Additionally, Figure 9 yes Figure 6 A variation of the above.

[0071] The basic structure of this embodiment is the same as that of Embodiment 1, and the description will focus on the differences from Embodiment 1.

[0072] In the semiconductor module 1 of this embodiment, as Figure 6 As shown, the position of the bonding end 13 of the side of the base 2 and the housing 7 is defined by the length (L1) from the center of the side of the base 2 to the end of the base 2, the length (L2) from the center of the side of the base 2 to the boundary between the first region 15 and the second region 16, the length (L3) from the center of the side of the base 2 to the end of the adhesive material 8 on the side of the base 2 that bonds the base 2 and the housing 7, and the thickness of the base 2.

[0073] In this embodiment, the wider region (first region) 15 of Al material 4 is provided such that the length in the x-direction of the wider region (first region) 15 of Al material 4 is greater than the thickness of the substrate 2, which is the difference between L1 and L2 (L1-L2). Furthermore, the position of the bonding end 13 is defined such that the difference between L2 and L3 (L2-L3) is greater than or equal to the difference between L1 and L2 (L1-L2) (L2-L3 ≥ L1-L2).

[0074] The length L3 of the adhesive part is shorter than the length of the housing 7, which can be achieved by controlling the amount and position of the adhesive material 8 during the housing bonding process.

[0075] Here, as described above, we consider the case where the temperature of the semiconductor module 1 changes from a high temperature to a low temperature. When the temperature of the semiconductor module 1 changes from a high temperature to a low temperature, in the region 15 where the width of the Al material 4 is wider (the length in the y-direction in the case of the long side), the Al material 4, which has a large coefficient of linear expansion, contracts in the x-direction. Therefore, due to this contraction, stress is generated in the region 17 where the circular marking portion on the side of the substrate 2 is stretched along the x-direction. Additionally, the shell 7, which has a large coefficient of linear expansion and is bonded to the side of the substrate 2, contracts in the x-direction. Therefore, stress is generated in the region 18 where the circular marking portion on the side of the substrate 2 is stretched along the x-direction.

[0076] However, in this embodiment, since the two regions 17 and 18 are sufficiently separated, the stresses generated will not overlap, and the stress generated on the surface of the Al material 4 on the side of the substrate 2 can be suppressed.

[0077] To confirm this effect, similar to the comparative example study described above, a thermal stress analysis was performed on the semiconductor module 1 of this embodiment. The analytical model, load conditions, etc., were the same as in the comparative example, and L2-L3, representing the position of the adhesive end 13, were used as parameters.

[0078] Figure 8 The results of the analysis are shown. The horizontal axis of the graph represents the value of (L2-L3) / (L1-L2), and the vertical axis represents the normalized value of the maximum stress on the surface of Al material 4 on the side of the substrate 2 when the maximum stress on the side of the substrate 2 is without side bonding.

[0079] like Figure 8 As shown, when (L2-L3) / (L1-L2) is greater than 1, the maximum stress value with side bonding is approximately equal to that without side bonding (relative value 1.0). The same result is obtained when studying L1-L2 with different values.

[0080] Therefore, in this embodiment where the condition L2-L3≥L1-L2 is met, the stress generated on the substrate 2 (AlSiC material 3 and Al material 4) at the bonding end 13 can be suppressed, thereby improving the structural reliability.

[0081] Furthermore, in this embodiment, the long side of semiconductor module 1 is also used ( Figure 4 The bonding area (on the x-direction side) is used as an example to explain the dimensional relationship and effect of the substrate 2, the housing 7, and the bonding part, but on the short side of the semiconductor module 1 ( Figure 4 The same dimensional relationship and its effect also hold true for the y-direction side.

[0082] Furthermore, in this embodiment, the key point is that the length L3 of the adhesive portion is shorter than L2, therefore an assumption is adopted. Figure 6 The diagram shows the case where the length of the shell 7 is longer than the length L3 of the adhesive portion. However, since the adhesive material 8 is prone to wetting and spreading, it can also be used as shown in the diagram. Figure 9 As shown in the modified example, consider a structure in which the length of the housing 7 is the same as the desired length L3 of the adhesive portion. Figure 9 The structure is configured such that the length from the center of the side of the base 2 to the end of the shell 7 opposite to the side of the base 2 is the same as that of L3.

[0083] However, in Figure 9In such a structure, the position of the adhesive end 13 also needs to be specified in such a way that the difference between L2 and L3 (L2-L3) is greater than or equal to the difference between L1 and L2 (L1-L2) (L2-L3≥L1-L2).

[0084] Example 3

[0085] Reference Figure 10 The semiconductor module of Embodiment 3 of the present invention will be described below. Figure 10 This is a bottom view of the semiconductor module in this embodiment, equivalent to that in Embodiment 1. Figure 4 .

[0086] The basic structure of this embodiment is the same as that of Embodiment 1, and the description will focus on the differences from Embodiment 1.

[0087] In the semiconductor module 1 of this embodiment, as Figure 10 As shown, when viewed from above, the Al material 4 is composed of a first region 15 disposed at the corners of the base 2 and the central part of the base 2 along its long side, and a second region 16 disposed on the outer periphery of the base 2 and narrower than the first region 15.

[0088] In addition, the position of the adhesive end 13 of the side of the base 2 and the shell 7 is defined by the length (L1) from the center of the side of the base 2 to the end of the base 2, the length (L2) from the center of the side of the base 2 to the boundary between the first region 15 and the second region 16, the length (L3) from the center of the side of the base 2 to the end of the adhesive material 8 on the side of the base 2 that bonds the base 2 and the shell 7, and the thickness of the base 2.

[0089] Furthermore, when viewed from above, the first regions 15 are disposed separately at the corners of the base 2 and at locations other than the corners. More specifically, the first regions 15 are disposed separately at the four corners of the base 2 and near the center of the two long sides of the base 2. The shell 7, opposite to the side of the base 2, is divided into two parts along the long side direction of the base 2, separated by the first regions 15 disposed near the center of the two long sides.

[0090] In this embodiment, similarly to Embodiment 1, the wider region (first region) 15 of Al material 4 is provided such that the difference between L1 and L2 (L1-L2), i.e., the length in the x-direction of the wider region (first region) 15 of Al material 4 is greater than the thickness of the substrate 2. Furthermore, the position of the adhesive end 13 is defined such that L3 is greater than or equal to L2 (L3≥L2).

[0091] Here, as described above, we consider the case where the temperature of the semiconductor module 1 changes from a high temperature to a low temperature. First, it can be assumed that the stress generated on the side surface of the substrate 2 near the first region 15 at the corner of the substrate 2 is greater than the stress generated on the side surface of the substrate 2 near the first region 15 at the center of the substrate 2 along its length. This is because the greater distance from the center of the module results in a greater effect from the thermal contraction of the housing 7.

[0092] Therefore, as Figure 10 As shown, even if the first region 15 exists outside the corner of the base 2, it is sufficient to evaluate the stress generated near the corner of the base 2. The mechanism of stress generation and the verification of the stress suppression effect in this embodiment are the same as those described in Example 1.

[0093] In addition, in this embodiment, the number of the wider regions (first regions) 15 of Al material 4 is set to six, but the same size relationship and its effect relationship also hold true in the case of more than six regions.

[0094] Example 4

[0095] Reference Figure 11 as well as Figure 12 The semiconductor module of Embodiment 4 of the present invention will be described below. Figure 11 This is a bottom view of the semiconductor module in this embodiment. Figure 12 yes Figure 11 The D-D' section view. Figure 11 and Figure 12 Each is equivalent to Example 1 Figure 4 and Figure 5 .

[0096] The basic structure of this embodiment is the same as that of Embodiment 1, and the description will focus on the differences from Embodiment 1.

[0097] In Example 1 ( Figure 4 and Figure 5 In this embodiment, the housing 7 is bonded to the upper surface and side surface of the substrate 2 via the upper surface portion 9 and the side surface portion 10 of the adhesive material 8. In contrast, the semiconductor module 1 of this embodiment differs from that of Embodiment 1. Figure 4 and Figure 5 The difference is that a gap 19 is provided between the side of the base 2 and the shell 7 without the adhesive material 8, and the shell 7 is bonded to the upper surface of the base 2 by the upper surface part 9 of the adhesive material 8.

[0098] That is, in this embodiment, as described in Embodiments 1 to 3, the length (L3) from the center of the edge of the base 2 to the end of the adhesive material 8 that bonds the base 2 and the shell 7 on the side of the base 2 is 0 (L3 = 0).

[0099] As in this embodiment, no adhesive material 8 is sandwiched on the side of the substrate 2. The shell 7 is bonded to the upper surface of the substrate 2 only by the upper surface portion 9 of the adhesive material. As a result, compared with other embodiments, the bonding strength between the substrate 2 and the shell 7 is reduced, but the stress generated on the substrate 2 (AlSiC material 3 and Al material 4) can be suppressed more reliably.

[0100] In addition, Figure 11 and Figure 12 The illustration shows an example where the adhesive material 8 is not sandwiched on any of the four sides of the substrate 2 along its long side (x-direction) and short side (y-direction). However, it is also possible to sandwich the adhesive material 8 on either side of the substrate 2 along its long side (x-direction) and short side (y-direction) and leave it off on the other side. In this case, the stress generated by the adhesive on the sides along the long side of the substrate 2 is more likely to increase, so it is preferable to sandwich the adhesive material 8 only along the short side.

[0101] Furthermore, in the above embodiments 1 to 4, the long side of the semiconductor module 1 ( Figure 1 The bonding area (on the x-direction side) is the focus, and the dimensional relationship and effect of the substrate 2, housing 7, and bonding portion are explained. However, on the short side of the semiconductor module 1 (… Figure 1 The same dimensional relationship and its effect also hold true for the y-direction side.

[0102] Therefore, for example, the short side (y-direction side) of the base 2 may satisfy L3≥L2 as described in Example 1, and the long side (x-direction side) of the base 2 may satisfy L2-L3≥L1-L2 as described in Example 2.

[0103] Furthermore, the present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are examples provided for easy understanding and explanation of the present invention, and are not limited to having all the structures. Additionally, a portion of the structure of one embodiment can be replaced with the structure of another embodiment, and structures of other embodiments can be added to the structure of one embodiment. Furthermore, for a portion of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0104] Symbol Explanation

[0105] 1—Semiconductor module, 2—Substrate, 3—AlSiC material, 4—Al material, 5—Fixing hole, 6—Fixing screw, 7—Housing, 8—Adhesive material, 9—Upper surface of adhesive material, 10—Side surface of adhesive material, 12—Housing protrusion, 13—Adhesive end, 14—Boundary between region 15 and region 16, 15—Wider area of ​​Al material 4 (first region), 16—Narrower area of ​​Al material 4 (second region), 17—Circular mark on the side of substrate 2, 18—Circular mark on the side of substrate 2, 19—Gap, 20—Circuit wiring pattern, 21—Lower surface conductor layer, 22—Insulating substrate, 23—Semiconductor chip, 24—Solder for substrate bonding, 25—Solder for chip bonding, 26—Silicone gel, 27—Cap, GS—Stress generated (relative value).

Claims

1. A semiconductor module comprising: a substrate; an insulating substrate bonded to the substrate; a semiconductor chip bonded to the insulating substrate; and a housing bonded to the substrate by an adhesive material. The semiconductor module is characterized by, The substrate is composed of a plate-shaped first material and a second material covering the first material, the second material having a greater coefficient of linear expansion than the first material. Viewed from above, the second material has: a first region disposed at a corner of the substrate; and a second region disposed at the outer periphery of the substrate and narrower than the width of the first region. The housing covers at least a portion of the side surface of the substrate, is bonded to the substrate at least on its upper surface by the adhesive material, and the coefficient of linear expansion of the housing is greater than that of the first material. When L1 is defined as the length from the center of the edge of the substrate to the end of the substrate, and L2 is defined as the length from the center of the edge of the substrate to the boundary between the first region and the second region, L1-L2 is thicker than the substrate plate. Let L3 be the length of the end of the base from the center of the edge of the base to the corner side of the base on the side surface of the base to which the adhesive material for bonding the base and the housing is bonded. When there is no adhesive material on the side surface of the base, when L3 = 0, L3 ≥ L2 or L2 - L3 ≥ L1 - L2 is satisfied.

2. The semiconductor module according to claim 1, characterized in that, The shorter side of the base satisfies L3≥L2. The long side of the substrate satisfies L2-L3≥L1-L2.

3. The semiconductor module according to claim 1, characterized in that, The first material is AlSiC. The second material is Al.

4. The semiconductor module according to claim 1, characterized in that, The length from the center of the edge of the base to the end of the housing opposite the side of the base is the same as that of L3.

5. The semiconductor module according to claim 1, characterized in that, When viewed from above, the first region is disposed separately at the corners of the base and at locations other than the corners of the base.

6. The semiconductor module according to claim 5, characterized in that, The first region is disposed separately at the four corners of the base and near the center of the two long sides of the base. The housing, which is opposite to the side of the base, is divided into two parts along the long side of the base by a first region located near the center of the two long sides.

7. The semiconductor module according to claim 1, characterized in that, L3 = 0, and there is no adhesive material between the substrate and the housing on the side of the substrate. The housing is bonded to the substrate on its upper surface by the adhesive material.

8. The semiconductor module according to claim 1, characterized in that, The housing has a protrusion that faces the side of the substrate across the adhesive material. The protrusion is configured to cover at least a portion of the side surface of the base.

9. The semiconductor module according to claim 3, characterized in that, The shell is made of PBT or PPS.

10. The semiconductor module according to claim 1, characterized in that, The semiconductor chip is a semiconductor chip equipped with an IGBT.

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