Module heat dissipation structure
The heat dissipation structure addresses the limitations of conventional modules by using a semiconductor package with a larger heat dissipation surface, a module housing with a wide opening, and an elastic thermal conductive sheet to enhance heat dissipation efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- MITSUBISHI ELECTRIC CORP
- Filing Date
- 2022-08-03
- Publication Date
- 2026-06-23
AI Technical Summary
Conventional module structures face limitations in reducing contact thermal resistance between the semiconductor package and the module housing, as well as the thermal resistance of the module housing, which hinders effective heat dissipation performance.
A heat dissipation structure comprising a semiconductor package with a larger heat dissipation surface, a module housing with a wide opening for screw-fastening, and an elastic thermal conductive sheet between the module housing and the module mounting structure, allowing efficient heat transfer without passing through the contact layer between the semiconductor package and the module housing.
The structure reduces contact thermal resistance and thermal resistance of the module housing, enhancing heat dissipation performance and enabling efficient heat dissipation to the module mounting structure.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a heat dissipation structure of a module incorporating a semiconductor package.
Background Art
[0002] As a conventional module structure, Patent Document 1 discloses a module housing having a dish-shaped hole on the outside, in which a package mounting a high heat generating component is attached with a female screw from the lower side of the package bottom surface to reduce the contact thermal resistance directly below and around the high heat generating component.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In the above conventional module structure, the bottom surface of the module housing is thermally contacted with a cooling plate for heat dissipation. However, in this case, there is a limit to reducing the contact thermal resistance between the package and the module housing, and a certain amount remains. In addition, there is a problem that the thermal resistance of the module housing does not necessarily contribute to reducing the thermal resistance, and the thermal resistance of the module housing remains.
[0005] The present disclosure has been made to solve the above problems, and aims to reduce the contact thermal resistance between the semiconductor package and the module housing, as well as the thermal resistance of the module housing, and improve the heat dissipation performance of the module.
Means for Solving the Problems
[0006] The heat dissipation structure of the module according to this disclosure comprises a semiconductor package including a semiconductor element mounting surface for mounting semiconductor elements and a base portion having a heat dissipation surface with a larger surface area than the semiconductor element mounting surface on the back side of the semiconductor element mounting surface; a module housing having a widely formed opening at the bottom and to which the base portion can be screw-fastened; and an elastic thermal conductive sheet disposed between the bottom surface of the module housing, the heat dissipation surface of the semiconductor package, and a module mounting structure on which the module housing is mounted. [Effects of the Invention]
[0007] The heat dissipation structure of the module disclosed herein reduces the contact thermal resistance between the semiconductor package and the module housing, as well as the thermal resistance of the module housing, thereby improving the heat dissipation performance of the module. [Brief explanation of the drawing]
[0008] [Figure 1] This is a plan view of the modular structure in Embodiment 1 with the cover removed. [Figure 2] This is a front view of the modular structure in Embodiment 1. [Figure 3] This is a cross-sectional view of the modular structure in Figure 1 along the line A-A. [Modes for carrying out the invention]
[0009] The embodiments of this disclosure will be described below with reference to the figures. In the following description, similar components will be denoted by the same reference numerals, and their names and functions will be the same or similar. Therefore, detailed descriptions of them may be omitted.
[0010] Embodiment 1. The module structure in Embodiment 1 will be described using Figures 1, 2, and 3. Figure 1 is a plan view of the module structure in Embodiment 1 with the cover 10 removed. Figure 2 is a front view of the module structure in Embodiment 1. Figure 3 is a cross-sectional view of the module structure in Figure 1 along line A-A. The module structure in Embodiment 1 comprises a cover 10, an RF connector 11, a DC connector 12, a PCA 13, devices 14a and 14b, semiconductor elements 20 included in devices 14a and 14b, bonding material 30, a semiconductor package 40, and a substrate 46 on which an RF pattern 47 is printed, a base portion 41, a seal ring 44, and a package cover 45 included in the semiconductor package 40, wires 43, ribbon wires 48, a module housing 50, a thermal conductive sheet 60, a module mounting structure 70, semiconductor package fastening screws 80, module fastening bolts 90, bolt holes 91, and an EMI gasket 100. The module housing 50 is a module case that houses the devices 14a and 14b. The heat dissipation structure of the module in Embodiment 1 comprises at least a semiconductor package 40, the module housing 50, and a thermal conductive sheet 60 placed between the module housing 50 and the module mounting structure 70. An EMI gasket 100 may also be included.
[0011] As shown in Figures 1 and 2, the module housing 50 contains a PCA 13 and one or more devices 14a, 14b, and its top is covered by a cover 10. The module housing 50 also has an RF connector 11 and a DC connector 12 on its side wall. Furthermore, the module housing 50 has bolt holes 91 around its periphery into which module fastening bolts 90 are inserted, and the module housing 50 is fastened to the module mounting structure 70 via a thermal conductive sheet 60, which will be described later, by the module fastening bolts 90. At this time, the cover 10 is placed on the upper surface of the module housing 50 and is fastened and fixed by the module fastening bolts 90. It is preferable to fasten eight bolt holes 91, as shown in Figure 1. However, the number and spacing of the bolt holes 91 shown in Figure 1 are not limited to the illustrated configuration.
[0012] Furthermore, a gasket that provides electromagnetic shielding may be attached to the contact surface between the cover 10 and the module housing 50. Here, the module mounting structure 70 is, for example, a satellite housing panel or a radar device mounted on a mobile body. The module mounting structure 70 may or may not be equipped with cooling means such as heat pipes.
[0013] Devices 14a and 14b include a semiconductor element 20, a bonding material 30, a semiconductor package 40, and a substrate 46 on which an RF pattern 47 is printed. Here, the semiconductor element 20 is, for example, a bare chip such as an FET (Field Effect Transistor) or an MMIC (Monolithic Microwave Integrated Circuit). The semiconductor element 20 of device 14a constitutes, for example, a high-power amplifier with high heat generation. Device 14b constitutes, for example, a multi-stage amplifier with lower output than a high-power amplifier. The substrate 46 is fitted into a through hole formed in the seal ring 44 and is a signal transmission substrate that transmits high-frequency RF (Radio Frequency) signals such as microwaves and millimeter waves while maintaining hermetically sealed inside and outside the semiconductor package 40. The material of the substrate 46 is, for example, ceramic.
[0014] As shown in Figure 3, the semiconductor package 40 of device 14a includes a base portion 41, a seal ring 44, and a package cover 45. The semiconductor element 20 and the substrate 46 are placed on the upper surface of the base portion 41. At this time, the semiconductor element 20 is attached to the base portion 41 via a bonding material 30.
[0015] The semiconductor element 20 and the substrate 46 are connected by gold wires 43, and if multiple devices are mounted, each substrate is connected by gold ribbon wires 48. In addition, the semiconductor element 20 and a portion of the substrate 46 are covered by a frame-shaped seal ring 44 and a flat package cover 45 attached to the top of the seal ring 44. In this case, the package cover 45 is bonded to the top surface of the seal ring 44 while maintaining airtightness.
[0016] In this embodiment, the base portion 41 has a convex cross-sectional shape. The surface of the base portion 41 to which the semiconductor element 20 is attached is defined as the semiconductor element mounting surface 41a. Also, the back surface side of the semiconductor element mounting surface 41a is defined as the heat dissipation surface 41b. The lower portion of the base portion 41 has a flange portion 42 that protrudes more than the upper portion. The flange portion 42 is sized to be fitted into an opening 51 of a module housing 50 described later and to be capable of being screw-fastened.
[0017] Also, the base portion 41 is made of a material having a linear expansion rate close to that of the materials used for the semiconductor element 20 and the substrate 46. The material is, for example, a composite material of copper and tungsten or copper and molybdenum. Also, the materials of the seal ring 44 and the package cover 45 are the same, and are formed of, for example, an iron-nickel-cobalt alloy, which is a material having a linear expansion coefficient close to that of ceramic.
[0018] The module housing 50 has an opening 51 formed with a wider lower part at the bottom. The semiconductor package 40 is screw-fastened to the opening 51 by a semiconductor package fastening screw 80. At this time, the heat dissipation surface 41b of the semiconductor package 40 is attached so as to protrude from the lower surface of the bottom of the module housing.
[0019] In this embodiment, the opening 51 has a convex cross-sectional shape into which the base portion 41 of the semiconductor package 40 can be fitted. The overhanging portion 52 that forms the upper part of the opening 51 having the convex cross-sectional shape forms a stepped surface facing the space of the opening 51. The upper part of the base portion 41 is fitted into the opening hole of the opening 51 located inside the overhanging portion 52. Also, the flange portion 42 of the base portion 41 is fitted into the opening hole of the opening 51 located below the overhanging portion 52, and the flange portion 42 is screw-fastened to the lower surface of the overhanging portion 52.
[0020] In this embodiment, the semiconductor package fastening screw 80 is attached in a direction from the semiconductor package 40 side toward the module housing 50. Note that the semiconductor package fastening screw 80 may be attached from the module housing 50 side toward the semiconductor package 40.
[0021] An EMI (Electro Magnetic Interference) gasket 100 containing conductive fibers, conductive particles, etc. may be attached between the opening 51 of the module housing 50 and the semiconductor package 40. When the semiconductor package 40 and the module housing 50 are screwed together by the semiconductor package fastening screw 80, the EMI gasket 100 is pressed against the semiconductor package 40.
[0022] The bottom lower surface 53 of the module housing and the heat dissipation surface 41b of the semiconductor package 40 are in contact with the module mounting structure 70 via an elastic heat conduction sheet 60. At this time, the heat conduction sheet 60 may be made of a material with high heat dissipation, and there is no special stipulation. For example, when it is desired to achieve conduction with GND like in a high-frequency module, a conductive graphite material is used, and when conductivity is not required, a silicone-based material is used. Also, there is no limit to the thickness as long as the step difference between the bottom lower surface 53 of the module housing and the heat dissipation surface 41b of the semiconductor package 40 can be absorbed, but it is usually 0.5 to 2 mm.
[0023] Next, the operation of the module structure configured as described above will be explained. When the semiconductor element 20 operates, the heat generated in the semiconductor element 20 is transmitted to the heat conduction sheet 60 via the bonding material 30, the base portion 41 of the semiconductor package 40, and the contact layer between the base portion 41 of the semiconductor package 40 and the heat conduction sheet 60. The heat transmitted to the heat conduction sheet 60 is transmitted to the module mounting structure 70 and dissipated. Thereby, the heat generated in the semiconductor element 20 is dissipated without passing through the contact layer between the semiconductor package 40 and the module housing 50 and the module housing 50.
[0024] Thus, in a module structure comprising a semiconductor package 40 including a semiconductor element mounting surface 41a on which the semiconductor element 20 is attached and a base portion 41 having a heat dissipation surface 41b on the back side of the semiconductor element mounting surface 41a having a larger surface area than the semiconductor element mounting surface 41a; a module housing 50 having an opening 51 at the bottom that is widely formed downwards, to which the base portion 41 can be screw-fastened; and an elastic thermal conductive sheet 60 disposed between the bottom surface 53 of the module housing 50, the heat dissipation surface 41b of the semiconductor package 40, and the module mounting structure 70 on which the module housing 50 is mounted, the heat generated in the semiconductor package 40 is dissipated to the module mounting structure 70 without passing through the contact layer between the semiconductor package 40 and the module housing 50, and the module housing 50. Therefore, it has the effect of preventing a decrease in heat dissipation due to the thermal resistance of the module housing 50.
[0025] When attaching the device 14a to the module housing 50, the module housing 50 can be inverted, and the device 14a can be fitted into the opening 51 from the back of the module housing.
[0026] The semiconductor package 40 can be easily removed by unscrewing the semiconductor package fastening screws 80. Therefore, compared to resin-encapsulated module structures found in IGBT modules and the like, this structure offers superior rework and maintenance capabilities, such as component replacement on a device-by-device basis.
[0027] Furthermore, by placing an elastic thermal conductive sheet 60 between the bottom surface 53 of the module housing and the heat dissipation surface 41b of the semiconductor package 40 and the module mounting structure 70, the thermal conductive sheet 60 deforms due to the pressing force when the module housing 50 and the module mounting structure 70 are fastened together by the module fastening bolts 90. As a result, the thermal conductive sheet 60 can absorb the difference in height between the bottom surface 53 of the module housing and the heat dissipation surface 41b of the semiconductor package 40. In addition, the semiconductor package 40 and the thermal conductive sheet 60, and the thermal conductive sheet 60 and the module mounting structure 70 can be pressed together and maintain contact. As a result, heat can be efficiently dissipated from the semiconductor package 40 to the thermal conductive sheet 60, and subsequently from the semiconductor package 40 to the module mounting structure 70.
[0028] In addition, in a module structure in which an EMI gasket 100 is provided between the opening 51 of the module housing 50 and the semiconductor package 40, electromagnetic shielding between the module housing 50 and the semiconductor package 40 becomes possible.
[0029] Furthermore, by using a material for the base portion 41 of the semiconductor package 40 that has a coefficient of thermal expansion similar to that of the semiconductor element 20 and the ceramic or other material of the substrate 46, it is possible to prevent the base portion 41 and the substrate 46 from deforming due to the heat generated by the semiconductor element 20, thereby preventing damage to the substrate 46.
[0030] In the embodiments described herein, the materials, dimensions, shapes, relative arrangements, or conditions for implementation of each component may be described. However, these are all illustrative examples and are not limited to those described in each embodiment. Therefore, countless variations not illustrated are conceivable within the scope of each embodiment. For example, this includes modifying, adding, or omitting any component, or even extracting at least one component from at least one embodiment and combining it with a component from another embodiment. In other words, it is possible to freely combine each embodiment or modify or omit each embodiment as appropriate.
[0031] Furthermore, to the extent that it does not create a contradiction, a component described as being provided as "one" in each of the above embodiments may be provided as "one or more." In addition, each component is a conceptual unit, including cases where one component is composed of multiple structures, and cases where one component corresponds to a part of a structure. [Industrial applicability]
[0032] The heat dissipation structure of the module according to this disclosure makes it possible to reduce the contact thermal resistance between the semiconductor package and the module housing, as well as the thermal resistance of the module housing. The semiconductor package can dissipate heat without going through the module housing, and the heat dissipation performance of the module can be improved. This heat dissipation structure is suitable for high-frequency modules when continuous transmission of high-frequency transmission signals is performed, or when a large amount of heat generation from the semiconductor is expected due to high-duty operation with a long transmission time per unit time, or when it is desirable to suppress the operating temperature of the semiconductor from a derating perspective. [Explanation of symbols]
[0033] 10 Cover, 11 RF connector, 12 DC connector, 13 PCA, 14 Device, 20 Semiconductor element, 30 Bonding material, 40 Semiconductor package, 41 Base part 41a Semiconductor element mounting surface, 41b Heat dissipation surface, 42 Flange, 43 Wire, 44 Seal ring, 45 Package cover, 46 Substrate, 47 RF pattern, 48 Ribbon wire, 50 Module housing, 51 Module housing opening, 52 Module housing protrusion, 53 Bottom surface of module housing, 60 Thermal conductive sheet, 70 Module mounting structure, 80 Semiconductor package fastening screw, 90 Module fastening bolt, 91 Bolt hole, 100 EMI gasket
Claims
1. A semiconductor package including a semiconductor element mounting surface for mounting semiconductor elements and a base portion having a heat dissipation surface with a larger surface area than the semiconductor element mounting surface on the back side of the semiconductor element mounting surface, A module housing having a wide opening at the bottom, into which the base portion can be screw-fastened, An elastic thermal conductive sheet is disposed between the bottom surface of the module housing and the heat dissipation surface and the module mounting structure on which the module housing is mounted, A heat dissipation structure for a module equipped with this feature.
2. The heat dissipation structure for a module according to claim 1, wherein the heat dissipation surface is mounted so as to protrude from the lower surface of the bottom of the module housing.
3. A heat dissipation structure for a module according to claim 1 or 2, wherein an EMI gasket is provided between the opening of the module housing and the semiconductor package.
4. The semiconductor package is a heat dissipation structure for a module according to claim 1, wherein the base portion is made of a composite material of copper and tungsten or copper and molybdenum, and the heat dissipation surface is in contact with the heat conductive sheet.