Semiconductor module, power conversion device, and method for manufacturing semiconductor module

Abstract

The present invention provides a semiconductor module (100) and the like. The semiconductor module (100) has a heat-conducting part (20) provided between a laminated substrate (5) on which a semiconductor chip (1) is placed and a cooler (30). The heat-conducting part (20) has a frame (21) and an opening (22). The opening (22) has a grease part (22a) and a space part (22b). The grease part (22a) is partially disposed in the opening (22) and contacts the laminated substrate (5) and the cooler (30). The space part (22b) is partially disposed between the grease part (22a) and the frame (21) and the space part is provided in a strip shape.

Description

Technical Field

[0001] The present invention relates to a semiconductor module having a circuit board connecting a semiconductor and a heat-conducting layer of a cooler, a power conversion device including the semiconductor module, and a method for manufacturing the semiconductor module. Background Technology

[0002] Power semiconductors, used as switching devices for power conversion, can sometimes be adversely affected by heat generated from the semiconductor chip. To mitigate this, heat-conducting layers and coolers are used in power semiconductor modules that incorporate power semiconductors.

[0003] For example, the heat generated when the power semiconductor in a power semiconductor element is working is transferred to the cooler via a thermally conductive layer between the semiconductor module and the cooler (heat sink), thereby cooling the heat-generating power semiconductor element.

[0004] Without a thermally conductive layer, warping or unevenness at the contact surface between the semiconductor module and the cooler can create an air layer with low thermal conductivity, preventing heat dissipation from the chip. Therefore, semi-solid thermally conductive layers such as grease are typically used. However, as the operating temperature Tjmax increases, grease leakage (pumping phenomenon) can occur during ΔTjP / C and ΔTcP / C tests, sometimes increasing the thermal resistance.

[0005] Patent document 1 discloses a grease that is easy to apply during application and is less prone to pumping out during reliability testing and actual use by changing the viscosity of the grease during and after application.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 5383599 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, the coating process requires additional steps such as mixing toluene and evaporating the coating material, increasing the number of steps and thus raising costs. Furthermore, setting the yield value of the grease viscosity at 20°C to 40 Pa or higher and 300 Pa or lower can suppress pumping phenomena. However, the temperature at which the grease is exposed varies depending on the size of the circuit board and the operating environment. Therefore, it is necessary to optimize the grease viscosity to suit these conditions.

[0011] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a semiconductor module with high heat dissipation performance that suppresses the outflow of lubricating grease (pumping phenomenon) and a method for manufacturing the same.

[0012] Methods for solving problems

[0013] To achieve the above objectives, the semiconductor module of the first aspect of the present invention is as follows: the semiconductor module comprises a multilayer substrate on which semiconductor elements are disposed and a cooler for cooling the multilayer substrate. The semiconductor module is characterized in that it includes a heat-conducting portion disposed between the multilayer substrate and the cooler. The heat-conducting portion includes a frame and an opening. The opening has: a grease portion partially disposed within the opening and filling the space between the multilayer substrate and the cooler; and a space portion partially disposed between the grease portion and the frame, and the space portion is configured as a strip.

[0014] In the semiconductor module of the present invention, a heat-conducting portion is disposed between the laminated substrate and the cooler, and heat generated by the semiconductor element is conducted to the cooler via the heat-conducting portion. The heat-conducting portion includes a frame and an opening, and the opening has a grease portion partially disposed within the opening. The grease portion fills the space between the laminated substrate and the cooler, thereby promoting heat dissipation.

[0015] Semiconductor modules, for example, when mounted on inverters, are mostly arranged parallel to the direction of gravity. Furthermore, since the grease in the grease compartment is semi-solid, grease leakage or pumping out can occur due to gravity. To prevent this, a strip-shaped space is provided between the grease compartment and the frame to collect the moved grease. Therefore, the semiconductor module of the present invention can maintain excellent heat dissipation performance while preventing grease leakage or pumping out.

[0016] In the semiconductor module of the first aspect of the present invention, it is preferred that the opening has two opposing sides, and the space is provided in such a way that it connects to one of the two sides and spans one end of the side and the other end.

[0017] The opening of the frame is, for example, rectangular, with two opposing sides. The space is arranged such that it connects to one of the two sides and continuously spans one end and the other end of that side (from end to end). Because the semiconductor module of the present invention forms a defined, strip-shaped space capable of receiving grease, it can prevent grease leakage.

[0018] Furthermore, in the semiconductor module of the first aspect of the present invention, it is preferable that the semiconductor element is arranged such that, when viewed from above, it is separated from the end of the grease portion adjacent to the space portion toward the center of the grease portion.

[0019] When viewed from above, the semiconductor elements are arranged separately from the ends of the grease portion towards the center of the grease portion, so that the semiconductor elements do not overlap with the space portion. That is, the semiconductor elements overlap with the grease portion when viewed from above, thus enabling efficient heat dissipation of the semiconductor elements (layered substrate).

[0020] Furthermore, in the semiconductor module of the first aspect of the present invention, it is preferable that the space portion occupies 5 to 10% of the area of ​​the opening.

[0021] Based on the above structure, the space of the heat-conducting part can ensure sufficient space to hold the lubricating grease after it has been moved.

[0022] Furthermore, in the semiconductor module of the first aspect of the present invention, it is preferable that the heat-conducting part has a frame having a comb-shaped portion protruding from the periphery of the side of the opening where the space portion is provided toward the grease portion.

[0023] According to this structure, the comb-shaped portion of the frame protrudes from the periphery of the side of the opening with the space portion toward the grease portion. As a result, the grease, which is compressed and pushed out, moves along the comb-shaped portion, thereby achieving grease homogenization and preventing grease leakage.

[0024] Furthermore, in the semiconductor module of the first aspect of the present invention, it is preferable that the Young's modulus Y1 of the frame is higher than the Young's modulus Y2 of the grease portion.

[0025] Based on this configuration, the frame is preferably made of a material with a high Young's modulus Y1 and good thermal conductivity, such as carbon sheets. Furthermore, since the Young's modulus Y2 of the grease portion is lower than that of the frame, a grease with high thermal conductivity and fluidity can be used.

[0026] Furthermore, in the semiconductor module of the first aspect of the present invention, it is preferred that the Young's modulus Y1 preferably satisfies the condition 5GPa≤Y1≤15GPa, and the Young's modulus Y2 preferably satisfies the condition 1Pa≤Y2≤200Pa.

[0027] By using a material that meets the above conditions, the heat-conducting part can reliably conduct the heat generated by the circuit board to the cooler when the heat-conducting part is deformed by pressing or when the circuit board warps.

[0028] Furthermore, in the semiconductor module of the first aspect of the present invention, it is preferable that the viscosity G of the grease portion satisfies the condition 60 Pa·s ≤ G ≤ 500 Pa·s.

[0029] By ensuring that the grease portion meets the above conditions, the heat-conducting portion can follow the warping when the heat-conducting portion is pressed and deformed or when the circuit board warps, and reliably conduct the heat generated by the circuit board to the cooler.

[0030] Furthermore, a second aspect of the present invention is a power conversion device, characterized in that any one of the semiconductor modules of the first aspect of the present invention is erected with the space portion above it.

[0031] According to this structure, when the semiconductor module is mounted inside the power conversion device, it is erected with the space of the frame at the top. Therefore, although the grease is subjected to a downward force due to gravity, it is prevented from flowing out because the space accommodates the grease.

[0032] Furthermore, a third aspect of the present invention is a method for manufacturing a semiconductor module, the semiconductor module comprising a multilayer substrate on which semiconductor elements are disposed and a cooler for cooling the multilayer substrate, the method for manufacturing the semiconductor module being characterized by comprising at least the following steps: a step of forming a heat-conducting portion, wherein the heat-conducting portion is disposed between the multilayer substrate and the cooler; a step of forming a grease portion, wherein the grease portion is partially disposed within an opening of a frame of the heat-conducting portion and fills the space between the multilayer substrate and the cooler; and a step of forming a space portion, wherein the space portion is partially disposed between the grease portion and the frame and the space portion is configured as a strip.

[0033] In the semiconductor module manufacturing method of the present invention, a heat-conducting portion is first fabricated between a multilayer substrate and a cooler. Then, a grease portion is partially formed within the opening of the heat-conducting portion. Since the grease portion fills the space between the multilayer substrate and the cooler, heat generated by the semiconductor element can be conducted to the cooler for heat dissipation.

[0034] Furthermore, in this manufacturing method, a space is locally formed between the grease portion and the frame, and this space is configured as a strip. Depending on the configuration of the semiconductor module, the grease may flow out due to gravity or be pumped out. To prevent this, the space is provided in advance at the opening, allowing the grease to move into the space. Therefore, the manufactured semiconductor module can prevent the grease from flowing out or being pumped out. Attached Figure Description

[0035] Figure 1 This is a cross-sectional view of the semiconductor module in an embodiment of the present invention.

[0036] Figure 2 yes Figure 1 A cross-sectional view of the R region.

[0037] Figure 3A This is a diagram illustrating the actual configuration of the semiconductor module.

[0038] Figure 3B This is a top-down view of the heat-conducting part of a semiconductor module.

[0039] Figure 4 It is a flowchart illustrating the manufacturing method of a semiconductor module.

[0040] Figure 5A yes Figure 3B A VA-VA cross-sectional view of the heat-conducting part.

[0041] Figure 5B yes Figure 3B VB-VB sectional view of the heat-conducting part.

[0042] Figure 6 This diagram illustrates the modification method of the heat-conducting part of the semiconductor module.

[0043] Explanation of reference numerals in the attached figures

[0044] 1, 1a-1g semiconductor chip; 2 wiring substrate; 4 pin; 5 laminated substrate; 8 housing; 9 screw; 10 module part; 11 resin part; 20, 25 heat-conducting part; 21 frame; 22 opening; 22a grease part; 22b space part; 23 comb-shaped part; 24 air layer; 30 cooler; 51 first conductive plate; 52 insulating substrate; 53 second conductive plate; 100 semiconductor module. Detailed Implementation

[0045] Hereinafter, embodiments of the semiconductor module of the present invention will be described with reference to the accompanying drawings. These embodiments can be appropriately modified and combined for application. Furthermore, in the following description and drawings, substantially the same or equivalent structures are labeled with the same reference numerals. It should be noted that the present invention is not limited to the embodiments described below.

[0046] The following description focuses on the case where semiconductor module 100 is a power semiconductor module in which power semiconductor elements are mounted. However, the present invention is applicable to semiconductor modules in which various semiconductor elements are mounted.

[0047] Figure 1 A cross-sectional view of a semiconductor module 100 according to an embodiment of the present invention is shown. The semiconductor module 100 comprises a module section 10, a cooler 30, and a heat-conducting section 20. A semiconductor chip 1, a wiring substrate 2, pins 4, and a laminated substrate 5 are disposed inside the module section 10 and sealed by a resin section 11. The cooler 30 dissipates heat generated by the module section 10. The heat-conducting section 20 is disposed between the module section 10 and the cooler 30 and conducts the generated heat to the cooler 30.

[0048] Semiconductor chip 1 is a power chip such as an IGBT (Insulated Gate Bipolar Transistor) or a diode chip, and various Si devices, SiC devices, GaN devices, etc. can be used. Furthermore, these devices can be combined. For example, a hybrid module using Si-IGBT and SiC-SBD can be used. The number of semiconductor chips 1 mounted is not limited to the form shown in the figure, and multiple chips can be mounted.

[0049] Wiring substrate 2 is disposed on the upper surface of semiconductor chip 1. Wiring substrate 2 has metal foil (metal wiring board) formed on both sides of an insulating substrate, with the metal foil on the lower surface facing the semiconductor chip 1. Wiring substrate 2 can also be a so-called printed circuit board. The insulating substrate is preferably made of a material with low dielectric constant and high thermal conductivity; for example, insulating resins such as Si3N4, AlN, and Al2O3 can be used. Furthermore, the metal foil is preferably made of a material with low electrical resistance and high thermal conductivity; for example, Cu can be used.

[0050] One end of pin 4 is bonded to the upper surface of semiconductor chip 1 via solder, and the other end is used for connection to wiring substrate 2, etc. Pin 4 can be made of a metal with low resistance and high thermal conductivity, such as Cu. Pin 4 is sometimes connected to the wiring substrate 2 on the upper surface or sometimes connected to the take-out terminal. It should be noted that pin 4 can also be connected to a lead frame. In addition to pin 4, the wiring extending from the upper surface of semiconductor chip 1 can also use a lead frame, wires made of Al, etc.

[0051] The laminated substrate 5 comprises an insulating substrate 52 located in the center, a first conductive plate 51 formed on one surface of the insulating substrate 52, and a second conductive plate 53 formed on the other surface of the insulating substrate 52. The insulating substrate 52 can be made of a material with excellent electrical insulation and thermal conductivity, such as Al2O3, AlN, and SiN. In particular, for high-voltage applications, a material that balances electrical insulation and thermal conductivity is preferred, such as AlN or SiN, but the application is not limited to these materials.

[0052] The first conductive plate 51 and the second conductive plate 53 can be made of metal materials such as Cu and Al, which have excellent conductivity and machinability. In this specification, the conductive plate facing the semiconductor chip 1 is designated as the first conductive plate 51, and the conductive plate facing the cooler 30 is designated as the second conductive plate 53. The second conductive plate 53 is sometimes referred to as the back copper foil. Alternatively, for purposes such as rust prevention, Cu or Al that has undergone Ni plating or similar treatments may be used. Methods for arranging the conductive plates on the insulating substrate 52 include direct copper bonding and active metal brazing.

[0053] As shown in the figure, the laminated substrate 5 is disposed on the lower surface side of the semiconductor chip 1. In the laminated substrate 5, the first conductive plate 51 and the second conductive plate 53 are electrically separated by the insulation of the insulating substrate 52. Preferably, the periphery of the insulating substrate 52 protrudes further outward than the periphery of the conductive plate.

[0054] The lower surface of the semiconductor chip 1 and the conductive plate (first conductive plate 51) on the upper surface of the laminated substrate 5 are electrically and thermally bonded by solder or the like. The conductive plate on the upper surface of the laminated substrate 5 is electrically separated from the conductive plate on the lower surface, but the thermal conductivity between the two conductive plates is good. In addition, the back copper foil on the lower surface of the laminated substrate 5 is bonded and in contact with the outer wall of the cooler 30 via the heat-conducting part 20.

[0055] Multiple semiconductor chips 1, wiring substrates 2, pins 4, and laminated substrates 5 are disposed inside the housing 8 of the module section 10. These components are sealed within the housing 8 using resin (resin section 11) through a potting or molding process. Furthermore, the module section 10 is fixed to the cooler 30 from the top surface side by screws 9. It should be noted that the surface of the cooler 30 opposite to the module section 10 is also referred to as the cooling surface.

[0056] The module 10, sealed by the resin section 11, is connected to the cooler 30 via the heat-conducting section 20. The heat-conducting section 20 is preferably made of a material with high thermal conductivity and includes a frame 21 and an opening 22. The opening 22 has a grease section 22a and a space section 22b partially disposed within it. It should be noted that in the module 10, the side where the second conductive plate 53 is exposed is also referred to as the back side of the module 10.

[0057] The opening 22 needs to be large enough to accommodate the second conductive plate 53 and further to accommodate the grease portion 22a and the space portion 22b. The opening 22 may also be smaller than the area of ​​the laminated substrate 5.

[0058] The frame 21 of this embodiment preferably has a specified Young's modulus (described in detail later), and is further preferably high thermal conductivity. The frame 21 of this embodiment is manufactured by processing carbon sheets or the like. The carbon sheet refers to a rigid sheet material with high thermal conductivity. The thickness of the carbon sheet is preferably about 200 μm to 1000 μm, and more preferably 300 μm to 500 μm from the viewpoint of thermal resistance and rigidity. The thermal conductivity of the carbon sheet is 10 to 40 W / mK, characterized in that it is higher than even soft thermally conductive materials such as grease (thermal conductivity: 1 to 4 W / mK).

[0059] Carbon sheets are sheet-like components made by compressing carbon-based materials, and can also be graphite sheets, etc. Here, "based" means that the carbon content is 90 wt% or more, excluding unavoidable impurities, or it can be composed of only carbon. Alternatively, it can be PAN (Polyacylonitrile) based, pitch-based carbon fibers, or materials in which carbon nanofibers are fixed into sheets. In these cases, from the viewpoint of density, the wire diameter of the carbon fibers is preferably 5 μm to 10 μm, and the wire diameter of the carbon nanofibers is preferably 1 nm to 50 nm.

[0060] Furthermore, the aforementioned carbon sheet can be a sheet composed solely of glassy carbon, or it can be a sheet containing resin in addition to carbon. When the resin is present, the carbon content is preferably 80 wt% to 99 wt%, and more preferably 90 wt% to 95 wt% from the viewpoint of thermal conductivity and elasticity. It should be noted that a lower carbon content than described above results in impaired formability, while a higher carbon content deteriorates thermal conductivity, and therefore is not preferred. Additionally, epoxy resin, phenolic resin, maleimide resin, etc., can be used as the resin.

[0061] The frame 21 in this embodiment can also be a material in which thermally conductive fillers other than carbon are incorporated into the resin. Specifically, it is a frame-shaped material formed by incorporating thermally conductive inorganic material particles such as silicon dioxide (SiO2), aluminum oxide (Al2O3), silicon nitride (SiN), and aluminum nitride (AlN) as fillers in materials such as epoxy resin, phenolic resin, maleimide resin, and silicone resin at a relative weight of 50wt% to 90wt% of the resin material, or metal particles such as Cu and Al.

[0062] The grease (thermal grease) is a semi-solid (flowable) material mainly composed of silicone resin, non-silicone resin, acrylic resin, etc., with insulating silicon nitride (SiN), alumina (Al2O3) particles mixed in as thermally conductive fillers. The grease portion 22a contacts the area where the semiconductor chip 1 is located and the cooler 30, thus conducting the heat generated on the semiconductor chip 1 to the cooler 30 for heat dissipation.

[0063] The grease containing thermally conductive filler is preferably electrically insulating. This is to prevent the grease from scattering and causing short circuits at the terminals of the module section 10. Therefore, ceramic is more preferred than metals such as copper and aluminum as the thermally conductive filler.

[0064] Alternatively, thermally conductive gels or similar paste-like TIM (Thermal Interface Material) materials can be used instead of grease.

[0065] The cooler 30 is, for example, a heat sink made of a material with good thermal conductivity such as Al or Cu. As the cooler 30, a heat sink consisting of multiple flow paths formed by multiple plate-shaped fins arranged in parallel can be used, or a metal plate can be used.

[0066] The semiconductor module 100 described above is located in the inverter control unit. At this time, the semiconductor module 100 is mostly arranged vertically (see reference). Figure 3A Vertical configuration refers to the arrangement of the back side of the semiconductor module 100, i.e., the long or short side, along the direction of gravity, and the cooling surface of the cooler 30 is also arranged along the direction of gravity.

[0067] Figure 2 express Figure 1 A magnified view of region R.

[0068] The semiconductor module 100 is used, for example, for power conversion, in which case the semiconductor chip 1 will generate heat. Therefore, it is necessary to keep the temperature of the semiconductor chip 1 and the laminated substrate 5 below a certain temperature, and a cooler 30 is installed on the back side of the module section 10 (resin section 11).

[0069] The surface of the module 10 that contacts the cooler 30 is macroscopically warped or undulating, and microscopically has fine bumps and depressions caused by the roughness of the contact surface, thus it is not smooth. Furthermore, the thermal expansion of the components caused by the heat generated by the semiconductor chip 1 deforms the shape (warped or undulating, fine bumps and depressions) of the surface of the module 10 opposite to the cooler 30 (the back surface of the module 10). Therefore, if an air layer 24 with low thermal conductivity without the heat-conducting part 20 is formed between the module 10 and the cooler 30, heat cannot be conducted, leading to an increase in thermal resistance. Therefore, the heat-conducting part 20 has a grease part 22a composed of semi-solid grease that can fill the air layer 24 and adhere well to the surface.

[0070] Figure 3A , Figure 3B This indicates the configuration of the semiconductor module 100 during use.

[0071] For example, when the semiconductor module 100 is configured within the inverter, such as Figure 3AAs shown, the semiconductor module 100 is arranged longitudinally. Consequently, the grease portion 22a of the heat-conducting section 20 is subjected to a downward force due to gravity. When the inverter is operating, the semiconductor module 100 is subjected to a temperature load, and the module portion 10 deforms due to the temperature rise, causing warping on the surface opposite the cooler 30. As a result, due to the thermal expansion of the grease and the grease being squeezed outward due to this warping, voids (pumping phenomenon) are created in the grease portion 22a.

[0072] Therefore, a space 22b is provided in advance in the opening 22 of the heat-conducting part 20 to allow the grease in the grease part 22a to move. In particular, when the space 22b is provided in a strip shape at the periphery of the end of the opening 22 on the side opposite to the direction of gravity (above), the lower part of the opening 22 is sealed, thus preventing the grease from flowing out. It should be noted that "strip shape" includes a rectangular shape, and when the outer edge of the space 22b side of the grease part 22a is a curved shape such as an arc or a corrugated shape, it includes a shape corresponding to that outer edge shape.

[0073] in addition, Figure 3B This figure shows an example of the heat-conducting portion 20 viewed from the upper surface of the semiconductor chip 1 (an example viewed from the left side on paper). As shown, two laminated substrates 5 are provided on the upper surface of the grease portion 22a, and semiconductor chips 1a-1d and 1e-1g are respectively disposed on their upper surfaces. One or more laminated substrates 5 may be included in the module portion 10, and one or more semiconductor chips 1 may be mounted on the laminated substrates 5.

[0074] like Figure 3B As shown, the frame 21 of the heat-conducting part 20 is shaped to match the shape of the module part 10, forming a shape with opposing sides L1 and L2 in the short side direction. The frame 21 is not limited to a rectangle, but can also be a polygon. However, the frame 21 is preferably the same shape as the module part 10, and more specifically, the same shape as the back surface of the module part 10.

[0075] Except for the space portion 22b, the opening 22 is filled with grease (grease portion 22a) with a Young's modulus lower than that of the frame 21 (Young's modulus Y1) (Young's modulus Y2).

[0076] Furthermore, the space portion 22b is formed at the periphery of the end opposite to the direction of gravity of the frame 21 when the semiconductor module 100 is arranged longitudinally. Figure 3B In the example, the space portion 22b is arranged in a strip shape, connected to the upper edge L1 of the frame 21, and uninterrupted from one end of the upper edge L1 in the short side direction to the other. When the frame is polygonal, the space portion 22b can be arranged to connect to at least one side in the short side direction.

[0077] exist Figure 3A , Figure 3B The diagram shows a configuration where the length of the semiconductor module 100 is parallel to the direction of gravity, but the same applies when the short side is parallel to the direction of gravity. Specifically, a space portion 22b can be provided on the side of the opening opposite to the direction of gravity.

[0078] Next, regarding Figure 3B The section spanning the semiconductor chip 1, the grease portion 22a, and the space portion 22b (section line VA-VA) will be described. When viewed from above (perspective view), the semiconductor chip 1a is positioned away from the end of the grease portion 22a adjacent to the space portion 22b towards the center of the grease portion 22a (details will be described later). This configuration allows the grease portion 22a to overlap with the semiconductor chip 1a, forming a non-overlapping positional relationship where the semiconductor chip 1a and the space portion 22b are separated. Preferably, the grease portion 22a is located below the semiconductor chip 1a, and the space portion 22b is absent. Therefore, when the grease is compressed and pushed out due to the module portion 10 being pressed against the cooler 30 side, or the cooler 30 being pressed against the semiconductor chip 1a side, the remaining grease can be contained in the space portion 22b.

[0079] exist Figure 3A In this configuration, the lower end of the space portion 22b is positioned above the upper end of the semiconductor chip 1. Furthermore, the space portion 22b is not located below the semiconductor chip 1 (see reference). Figure 1 Therefore, a grease section 22a needs to be continuously provided. Heat generated on the semiconductor chip 1 is dissipated by the cooler 30 via the grease section 22a after passing through the laminated substrate 5 disposed below the semiconductor chip 1. It should be noted that... Figure 3A , Figure 3B The bottom of the image represents the direction of gravity, while the top represents the direction opposite to gravity.

[0080] exist Figure 3A Preferably, the upper end of the laminated substrate 5, such as the upper end of the insulating substrate 52, is positioned below the lower end of the space portion 22b. Furthermore, when viewed from above (perspective view), it is preferable that the second conductive plate 53 of the laminated substrate 5 is arranged in a manner that does not overlap with (is not exposed) the space portion 22b.

[0081] The Young's modulus Y1 of the frame 21 preferably satisfies the condition 5 GPa ≤ Y1 ≤ 15 GPa, and the Young's modulus Y2 of the grease portion 22a preferably satisfies the condition 1 Pa ≤ Y2 ≤ 200 Pa. The viscosity G of the grease only needs to satisfy the condition 60 Pa·s ≤ G ≤ 500 Pa·s at 25°C. By satisfying the above conditions for the frame 21 and the grease portion 22a, when the heat-conducting portion 20 (frame 21) is deformed by being pressed, or when warping occurs on the semiconductor chip 1, the heat generated on the semiconductor chip 1 can be reliably conducted to the cooler 30 following the warping.

[0082] Furthermore, the structure of the heat-conducting part 20 described above prevents grease sagging. The grease temporarily moves towards the space 22b due to the deformation of the module part 10. However, it gradually returns to its original position due to gravity (its own weight), thus preventing problems caused by pumping out. Therefore, a heat-conducting part 20 can be provided that suppresses grease outflow and pumping, thereby suppressing the increase in thermal resistance.

[0083] Here, refer to Figure 4 The manufacturing method of the semiconductor module 100 of the present invention will be briefly described below.

[0084] First, the material of the heat-conducting part 20 is processed into a frame shape (step 10). For example, a carbon sheet is processed into a frame shape having an opening 22 of a size that can accommodate multiple semiconductor chips 1. Additionally, holes for fastening parts such as screws are formed in this material. Preferably, the carbon sheet is a highly flexible carbon sheet with a thickness of approximately 300 μm to 500 μm and a thermal conductivity similar to that of Cu (400 W / mK) (see reference). Figure 3B ).

[0085] Next, lubricating grease is applied to the lower surface of the module 10 (step 20). Specifically, lubricating grease is applied to designated locations on the module 10 using a dedicated mask.

[0086] Next, the heat-conducting part 20 (frame 21) is disposed on the lower surface of the module part 10 (step 30). Here, adjustments are made so that the grease is disposed in the opening 22. The space part 22b is set to occupy 5 to 10% of the area of ​​the opening 22. As a result, the space part 22b can fully accommodate the moved grease.

[0087] Next, the module 10, equipped with the heat-conducting part 20 (containing lubricating grease), is placed on the cooling surface of the cooler 30 (step 40 / STEP 40). Finally, the module 10, the heat-conducting part 20, and the cooler 30 are fastened using screws 9 (step 50 / STEP 50). At this time, the lubricating grease and the heat-conducting part 20 will deform to some extent depending on the mating surface. Furthermore, the thickness of the heat-conducting part 20 is approximately 20 μm to 100 μm. Through the above method, the following is completed: Figure 1 The semiconductor module 100 of the present invention is shown.

[0088] The preferred embodiment of the semiconductor module 100 will be described below. Figure 5A express Figure 3B A VA-VA cross-sectional view of the heat-conducting part 20.

[0089] like Figure 5A As shown, the end of the grease portion 22a adjacent to the space portion 22b is designated as E. Furthermore, the end of the semiconductor chip 1a near end E is designated as F, and the intersection of the perpendicular line from end F to the grease portion 22a and the grease portion 22a is designated as point H. At this time, distance EH is set as d1 (the separation distance between the semiconductor chip 1a and the space portion 22b), and distance FH is set as d2.

[0090] In order to efficiently conduct the heat generated by the semiconductor chip 1a to the cooler 30, when viewed from above, the semiconductor chip 1a needs to be arranged separately from the end E of the grease portion 22a towards the center of the grease portion 22a (to the right in the figure) (d1≠0). This is because there is no heat conduction effect in the space portion 22b. Considering the thermal conductivity, it is preferable to determine the position of the end F of the semiconductor chip 1a in a way that ∠EFH is greater than 45 degrees. That is, the amount of grease is determined in such a way that the distance from d1 is greater than or equal to the distance from d2, or the semiconductor chip 1a can be arranged. Furthermore, from the viewpoint of heat dissipation, it is preferable that the entire back surface of the second conductive plate 53 of the laminated substrate 5 is in contact with the grease portion 22a and does not leak out of the space portion 22b.

[0091] Figure 5B express Figure 3B A VB-VB cross-sectional view of the heat-conducting part 20. (See figure) Figure 5B As shown, the end of the grease portion 22a adjacent to the frame 21 is designated as I. Furthermore, the end of the semiconductor chip 1g near end I is designated as J, and the intersection of the vertical line from end J to the grease portion 22a and the grease portion 22a is designated as point K. At this time, distance IK is set to d3 (the separation distance between the semiconductor chip 1g and the end of the grease portion 22a (the side without the space portion 22b)), and distance JK is set to d4.

[0092] Similar to the VA-VA cross-section, in order to efficiently conduct the heat generated on the semiconductor chip 1g to the cooler 30, when viewed from above, the semiconductor chip 1g needs to be positioned separately from the end I of the grease portion 22a towards the center of the grease portion 22a (to the left in the figure) (d3≠0). This is because the grease portion 22a has a higher thermal conductivity than the frame 21. Preferably, the position of the end J of the semiconductor chip 1g is determined with ∠IJH greater than 45 degrees. That is, the semiconductor chip 1g is positioned such that the distance from d3 is greater than or equal to the distance from d4.

[0093] exist Figure 5A , Figure 5B The diagram shows a cross-sectional view of the end of the opening 22 along its long side. However, the same applies to the case where the module 10 is arranged in the inverter control unit with its short side in the direction of gravity. For example, when the distance from the end of the semiconductor chip 1g along its short side to the end of the space 22b along its short side (the closer one) is set to d5, the distance d5 is preferably a distance greater than or equal to d2 or d4.

[0094] Finally, refer to Figure 6 The method of modifying the heat-conducting part of the semiconductor module 100 is explained.

[0095] When viewed from above, the heat-conducting part 25 has a comb-shaped part 23 protruding from the periphery of the side of the opening 22 where the space portion 22b is provided toward the grease portion 22a. It should be noted that the portion of the comb-shaped part 23 located below the laminated substrate 5 is indicated by dashed lines.

[0096] The comb-shaped portion 23 is provided with a slit portion that covers a portion of the grease portion 22a and the space portion 22b. Therefore, when the grease is pushed and spread out by the cooler 30 being pressed towards the semiconductor chip 1a, the grease moves along the gap (slit portion) of the comb-shaped portion 23.

[0097] Preferably, such as Figure 3A As shown, when the semiconductor module 100 is viewed in cross-section, a grease portion 22a is continuously arranged on the left side of the semiconductor chip 1a without any space portion 22b. Therefore, it is preferable that the lower end of the slit portion is... Figure 6 It is positioned above the semiconductor chip 1a.

[0098] Furthermore, preferably, the lower end of the slit portion is at Figure 6 It is positioned above the second conductive plate 53. More preferably, the lower end of the slit is located above... Figure 6 It is positioned above the upper end of the laminated substrate 5.

[0099] Because of the presence of the comb-shaped portion 23, a narrow slit is formed, allowing the grease to move smoothly within the slit, thus ensuring uniform grease movement. This prevents the grease from leaking out and suppresses pumping phenomena. The space 22b containing the slit portion of the comb-shaped portion 23 preferably occupies 5-10% of the area of ​​the opening 22.

[0100] The embodiments for implementing the present invention have been described above, but the present invention is not limited to the above embodiments, and appropriate changes can be made without departing from the spirit of the present invention.

[0101] In the above embodiment, the space portion 22b of the heat-conducting portion 20 exists on the upper side when the semiconductor module 100 is arranged longitudinally, but it is not limited to this method. For example, if the warping direction of the semiconductor chip 1 is known in advance, the space portion can be provided in a strip shape on a portion of the periphery of the opening 22 in the warping direction.

Claims

1. A semiconductor module comprising a multilayer substrate on which semiconductor elements are disposed and a cooler for cooling the multilayer substrate, characterized in that, It includes a heat-conducting portion disposed between the laminated substrate and the cooler. The heat-conducting part has a frame and an opening. The opening has: a grease portion partially disposed within the opening and filling the space between the laminated substrate and the cooler; and a space portion partially disposed between the grease portion and the frame, the space portion being strip-shaped. The frame is located only below the laminated substrate in the cross-sectional view.

2. The semiconductor module according to claim 1, characterized in that, The opening has two opposing sides. The space is arranged such that it connects to one of the two sides and spans one end of the side and the other end.

3. The semiconductor module according to claim 1 or 2, characterized in that, When viewed from above, the semiconductor element is arranged such that it is separated from the end of the grease portion adjacent to the space portion toward the center of the grease portion.

4. The semiconductor module according to claim 1 or 2, characterized in that, The space occupies 5 to 10% of the area of ​​the opening.

5. The semiconductor module according to claim 1 or 2, characterized in that, The Young's modulus Y1 of the frame is higher than that of the grease portion Y2.

6. The semiconductor module according to claim 5, characterized in that, The Young's modulus Y1 satisfies the condition 5GPa≤Y1≤15GPa.

7. The semiconductor module according to claim 5, characterized in that, The Young's modulus Y2 satisfies the condition 1Pa≤Y2≤200Pa.

8. The semiconductor module according to claim 1 or 2, characterized in that, The viscosity G of the grease portion satisfies the condition 60 Pa·s ≤ G ≤ 500 Pa·s.

9. The semiconductor module according to claim 1, characterized in that, The grease portion is partially in contact with the inner side of the frame.

10. A semiconductor module comprising a multilayer substrate on which semiconductor elements are disposed and a cooler for cooling the multilayer substrate, characterized in that, It includes a heat-conducting portion disposed between the laminated substrate and the cooler. The heat-conducting part has a frame and an opening. The opening has: a grease portion partially disposed within the opening and filling the space between the laminated substrate and the cooler; and a space portion partially disposed between the grease portion and the frame, the space portion being strip-shaped. The heat-conducting part has a frame with a comb-shaped portion protruding from the periphery of the side of the opening where the space portion is provided toward the grease portion.

11. A power conversion device, characterized by, The semiconductor module according to claim 1 or 2 is erected with the space portion above it.

12. A method for manufacturing a semiconductor module, the semiconductor module comprising a multilayer substrate on which semiconductor elements are disposed and a cooler for cooling the multilayer substrate. The method for manufacturing the semiconductor module is characterized by having at least the following features: a step of producing the heat conducting portion, wherein The heat-conducting part is disposed between the laminated substrate and the cooler; The step of forming a grease portion, wherein the grease portion is partially disposed within an opening in the frame of the heat-conducting portion and fills the space between the laminated substrate and the cooler; and, The step of forming a space portion includes a space portion that is partially disposed between the grease portion and the frame, and the space portion is configured as a strip. The frame is located only below the laminated substrate in the cross-sectional view.

13. The semiconductor module according to claim 12, characterized in that, The grease portion is partially in contact with the inner side of the frame.

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