Semiconductor device

Abstract

In the prior art, a heat radiation path is not uniform and heat cannot be fully transmitted to a fin because a heat radiation fin cannot fully warp along with a bottom plate on the back surface of a semiconductor module and the contact area between the heat radiation fin and the bottom plate is insufficient relative to the area of the bottom plate. Accordingly, an object of the present disclosure is to provide a heat sink capable of transferring heat to a fin by sufficiently securing a contact area between the heat sink and a base plate. A semiconductor device according to the present disclosure includes: an insulating substrate; a semiconductor element bonded to one side surface of the insulating substrate; and a bottom plate, one side surface of which is bonded to the other side surface of the insulating substrate, and the other side surface of which has warpage; the heat dissipation sheet is connected with the surface of the other side of the bottom plate in an abutting mode, the heat dissipation sheet is of a solid structure, and the shape of the surface of one side of the heat dissipation sheet follows the warping shape of the bottom plate.

Description

Technical Field

[0001] This disclosure relates to semiconductor devices. Background Technology

[0002] For example, Patent Document 1 discloses an apparatus characterized in that a bonding layer containing a thermo-pressing adhesive is provided between a semiconductor module and a heat sink, and between the heat sink and a cooling device disposed on the surface of the heat sink opposite to the semiconductor module.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2018-133527 Summary of the Invention

[0004] The technical problem that the invention aims to solve In the aforementioned prior art, there is a problem that the heat sink cannot fully follow the warping of the base plate on the back of the semiconductor module, and the contact area between the heat sink and the base plate is insufficient relative to the area of ​​the base plate. Therefore, the heat dissipation path is uneven, and heat cannot be fully transferred to the fins.

[0005] Therefore, the object of this disclosure is to provide a heat sink that can improve heat dissipation efficiency by increasing the contact area between the base plate having warps and the heat sink.

[0006] Technical means for solving technical problems The semiconductor device disclosed herein includes: an insulating substrate; a semiconductor element bonded to one side surface of the insulating substrate; a base plate having one side surface bonded to another side surface of the insulating substrate, and the other side surface of the base plate having warpage; and a heat sink abutting against the other side surface of the base plate, the heat sink being solid, and the shape of one side surface of the heat sink following the warpage shape of the base plate.

[0007] Invention Effects According to the semiconductor device of the present invention, by forming a heat sink along the warping of the base plate, the contact area between the heat sink and the base plate is increased, thereby improving the heat dissipation efficiency. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view of the semiconductor device according to Embodiment 1.

[0009] Figure 2 This is a cross-sectional view of the semiconductor device according to Embodiment 1.

[0010] Figure 3This is a bottom view of the heat sink in the semiconductor device according to a variation of Embodiment 1.

[0011] Figure 4 This is a cross-sectional view of the semiconductor device according to Embodiment 2.

[0012] Figure 5 This is a bottom view of the heat sink in the semiconductor device according to Embodiment 2. Detailed Implementation

[0013] 1. Implementation Method 1 The semiconductor device 1 according to Embodiment 1 will be described with reference to the accompanying drawings. Figure 1 This is a cross-sectional view of the semiconductor device 1 according to Embodiment 1. Figure 2 This is a cross-sectional view of the semiconductor device 1 according to Embodiment 1. Figure 3 This is a bottom view of the heat sink 16 in the semiconductor device 1 according to a variation of Embodiment 1.

[0014] 1-1. Structure of Semiconductor Device 1 The semiconductor device 1 includes: an insulating substrate 2; a semiconductor element 7, which is bonded to one side surface of the insulating substrate 2; a base plate 3, one side surface of which is bonded to the other side surface of the insulating substrate 2, and the other side surface of the base plate 3 is warped; and a heat sink 16, which abuts against the other side surface of the base plate 3, the heat sink 16 being a solid structure, and the shape of one side surface of the heat sink 16 following the warped shape of the base plate 3.

[0015] In this disclosure, the direction perpendicular to the direction in which the base plate 3 and the heat sink 16 are joined is defined as the first direction.

[0016] <Insulating substrate 2> In this embodiment, a semiconductor element 7 is bonded to one surface of the insulating substrate 2, and a base plate 3 is bonded to the other surface. The substrate 2 is made of ceramic, resin, or the like. The insulating substrate 2, the base plate 3, and the semiconductor element 7 are bonded using a bonding material 4 such as solder. A circuit pattern is formed on the insulating substrate 2. For example, the circuit pattern is formed by etching copper or the like.

[0017] For example, an insulating substrate consists of a circuit board and an insulating plate. The insulating substrates are stacked in the order of circuit board, insulating plate, circuit board, with the insulating plate sandwiched between two circuit boards. The circuit board is primarily made of copper and forms the circuit pattern. The insulating plate is made of insulating ceramic materials such as alumina. By sandwiching the insulator between the two circuit boards, the individual circuits formed by the two types of circuit boards do not interfere with each other, preventing short circuits and electrical problems.

[0018] A bonding material is applied to both surfaces of an insulating substrate (one surface of one circuit board and the other surface of the other circuit board). While solder is primarily used as the bonding material, sintered materials, such as metal pastes like silver paste, can also be used. Semiconductor components or capacitor chips are mounted on one surface of the insulating substrate with the bonding material, and a heat sink is mounted on the other surface with the bonding material.

[0019] Multiple insulating substrates are connected to each other via bonding wires. On one side surface of each insulating substrate, the end of the bonding wire is mounted in a manner that connects to a circuit board.

[0020] <Semiconductor Components 7> In this embodiment, the semiconductor element 7 is bonded to one side surface of the circuit pattern formed on the insulating substrate 2. The semiconductor element 7 uses an IGBT (Insulated Gate Bipolar Transistor), a diode, or the like. The semiconductor element 7 is connected to electrode terminals mounted on the housing using wires. The wires are made of, for example, copper or aluminum.

[0021] For example, a semiconductor element is bonded to one surface of an insulating substrate. The other surface of the semiconductor element is mounted to one surface of the insulating substrate via a bonding material.

[0022] One end of the bonding wire is bonded to one side surface of the semiconductor device. The other end of the bonding wire is bonded to an external terminal. The semiconductor device is electrically connected to the outside via the bonding wire.

[0023] The semiconductor element used in this example is an IGBT. IGBTs are used for high-voltage, high-current switching, in applications such as motor control and inverter circuits. However, semiconductor elements can be more than just IGBTs; they can also be types such as MOSFETs.

[0024] <Base Plate 3> In this embodiment, the other side surface of the insulating substrate 2 is bonded to one side surface of the base plate 3. The base plate 3 has warping on the other side surface. The base plate 3 uses copper or aluminum as the main material. In this embodiment, the warping is a convex warping where the protrusion height increases as it approaches the center. The other side surface of the base plate 3 has a convex spherical warping. Alternatively, as shown in Embodiment 2, the warping can be a convex warping where the protrusion height increases as it approaches the center in a specific first direction. In this case, the other side surface of the base plate 3 has a cylindrical spherical warping.

[0025] <Other Structures of Semiconductor Device 1> In this embodiment, the semiconductor device 1 is surrounded by a resin housing 11. The resin housing 11 is a generally rectangular box shape. It is configured to house the insulating substrate 2 and the semiconductor element 7 inside, and even if liquid sealing material 13 or the like flows into the resin housing 11, the liquid sealing material 14 or the like will not flow out to the outside. The resin housing 11 is made of a resin such as PPS (polyphenylene sulfide). Other resins can be used instead of PPS (polyphenylene sulfide).

[0026] As described above, one end of the bonding wire 12 is mounted to a portion of one side surface of the semiconductor element 7. The other end of the bonding wire 12 is connected to one end of the circuit board 5. The circuit board 5 abuts against the external terminal 8, which extends along the inner surface of the resin housing 11, and the other end of the external terminal 8 protrudes from the resin housing 11 and the sealing material 13 to the outside. The external terminal 8 exposed to the outside contacts other components, thereby enabling connection to external components.

[0027] Semiconductor element 7, insulating substrate 2, and bonding wire 12 are surrounded by resin housing 11 and base plate 3. Sealing material 13 is filled inside resin housing 11 and heat sink to protect semiconductor element 7, insulating substrate 2, etc.

[0028] <Heater 16> In this embodiment, the heat sink 16 abuts against the other side surface of the base plate 3. The heat sink 16 is solid, and the shape of one side surface of the heat sink 16 follows the warped shape of the base plate 3. With this structure, the heat sink 16 can make full contact with the area of ​​the other side surface of the base plate 3. Through this full contact, the heat present in the base plate 3 can be effectively dissipated via the heat sink 16. The dissipated heat is transferred to the fins, which serve as a cooler 9, which are bonded to the other side surface of the heat sink 16, thereby cooling the semiconductor device 1. Furthermore, even when the heat sink 16 and the base plate 3 are disassembled, one side surface of the heat sink 16 retains the shape that follows the warped shape of the base plate 3.

[0029] In this embodiment, the portion of the heat sink 16 that abuts against the base plate 3 is not adhesive. With this structure, placing the adhesive portion on the resin housing 11 reduces the impact on heat dissipation compared to placing the adhesive portion on the base plate 3, which is exposed on the other side of the semiconductor device 1.

[0030] In this embodiment, the portion of the heat sink 16 that does not abut against the base plate 3 is adhesive and bonded to the base plate 3 (in this example, the resin housing 11). Since the semiconductor device 1 generates the most heat directly beneath the semiconductor element 7, effectively dissipating this heat is crucial for cooling the semiconductor device 1. Therefore, in this embodiment, the bonding portion, which has a lower thermal conductivity than the heat sink 16, is positioned to avoid the base plate 3 directly beneath the semiconductor element 7. This structure improves heat dissipation efficiency.

[0031] In this embodiment, the heat sink 16 has mounting holes 17 in the portion that does not abut against the base plate 3, and the heat sink 16 is fixed to the side of the base plate 3 (in this example, the resin housing 11) using the mounting holes 17. For example, the heat sink 16 is fixed to the resin housing 11 by inserting fastening members such as screws or bolts into the mounting holes 17. With this structure, the semiconductor device 1 can be mounted to the cooler 9 while the heat sink 16 is bonded. As a result, the positioning of the semiconductor device 1 and the heat sink 16 can be omitted.

[0032] In this embodiment, the heat sink 16 contains graphite as a component. Graphite has high thermal conductivity and is widely used as the material for the heat sink 16. Furthermore, the heat sink 16 is formed with a hardness in the range of 30 to 70 degrees (Type E). This structure improves heat dissipation efficiency. Additionally, graphite exhibits anisotropic thermal conductivity, and the graphite layer is arranged longitudinally relative to the base plate 3. This structure further enhances the thermal conductivity of the graphite. Graphite may not necessarily possess anisotropic thermal conductivity.

[0033] In this embodiment, the thickness of the heat sink 16 varies depending on the warping of the base plate 3. Furthermore, the thickness of the heat sink 16 decreases as the protrusion height of the other side surface of the base plate 3 increases. With this structure, while one side surface of the heat sink 16 follows the warping, the other side surface of the heat sink 16 can remain flat, allowing the other side surface of the heat sink 16 to be engaged when the fins serving as the cooler 9 are mounted to it.

[0034] In a variation of this embodiment, the heat sink 16 is composed of two pieces of different thicknesses. For example... Figure 2 As shown, the second heat sink 16b on the side of the base plate 3 overlaps with the first heat sink 16a on the opposite side of the base plate 3. One surface of the second heat sink 16b follows the warped shape of the base plate 3, while the other surface of the second heat sink 16b is flat and joins to one surface of the first heat sink 16a. The first heat sink 16a is formed in a flat plate shape and is larger than the second heat sink 16b. Since the heat sink 16 is mainly composed of graphite, grinding is difficult, and it is difficult to produce variations in thickness on a single sheet. This structure allows for easy processing of heat sinks 16 with varying thicknesses. Furthermore, as... Figure 3 As shown, a first heat sink 16a with a perforation formed in the center and a second heat sink 16b that matches the shape of the perforation are constructed. The second heat sink 16b is opposite to the base plate 3 and its shape follows the warped shape of the base plate 3.

[0035] 2. Implementation Method 2 The semiconductor device 1 according to Embodiment 2 will be described with reference to the accompanying drawings. Figure 4 This is a cross-sectional view of the semiconductor device 1 according to Embodiment 2. Figure 5 This is a bottom view of the heat sink 16 in the semiconductor device according to Embodiment 2.

[0036] The heat sink 16 according to this embodiment has multiple slits. According to this structure, when the heat sink 16 is pressed onto the base plate 3, the thickness of the portion of the heat sink 16 adjacent to the slit easily changes due to the variation in the width of the slits, and the heat sink easily warps and deforms along the convex shape of the base plate 3. Furthermore, the contact surface is larger, thus improving heat dissipation efficiency. Additionally, the shape of the slits can be curved or polygonal.

[0037] The warping of the substrate 3 in this embodiment is a convex warping where the protrusion height increases as it approaches the center. The other side surface of the substrate 3 has a cylindrical spherical warping. According to this structure, the substrate 3 of the semiconductor device 1 has a convex warping with the greatest protrusion height at the center in the first direction. Furthermore, similar to Embodiment 1, the other side surface of the substrate 3 may also have a convex spherical warping.

[0038] In this embodiment, the width of the slits increases as the protrusion height of the warped portion opposite each slit increases. According to this structure, since the base plate 3 of the semiconductor device 1 has a warped shape with the largest protrusion height at its center, by widening the slit spacing at the center of the heat sink 16, sufficient space can be ensured for the heat sink 16 to extend into the slits in areas with greater protrusion height and pressure, thus facilitating deformation along the warp. The slit spacing narrows towards the end of the base plate 3. This structure reduces the gap between the heat sink 16 and the base plate 3 in areas with less pressure and less deformation. Furthermore, by reducing the gap, heat dissipation efficiency can be improved.

[0039] The warping involved in this embodiment is warping with different protrusion heights at various positions in the first direction, and multiple slits are arranged in the first direction. According to this structure, by aligning the first direction with which the protrusion heights differ with the arrangement direction of the multiple slits, the heat sink 16 can be easily deformed according to the different protrusion heights at various positions in the first direction.

[0040] When the protrusion height of the warp varies due to individual differences, the width of the multiple slits of each individual can be varied according to the deviation of the protrusion height of each individual. That is, for each individual, the width of the slit can be varied according to the protrusion height of the warp portion opposite to each slit, so that the width of the slit increases as the protrusion height of the warp portion opposite to each slit increases. Even if individual differences occur in the protrusion height due to position, the heat sink 16 can be deformed appropriately so that the heat sink 16 follows the warp of the base plate 3.

[0041] Label Explanation 1 Semiconductor device, 2 Insulating substrate, 3 Base plate, 4 Bonding material, 5 Circuit board, 7 Semiconductor element, 8 External terminal, 9 Cooler (fin), 11 Resin housing, 12 Bonding wire, 13 Sealing material, 16 Heat sink, 16a First heat sink, 16b Second heat sink, 17 Mounting hole.

Claims

1. A semiconductor device, characterized in that, include: Insulating substrate; A semiconductor element, which is bonded to one side surface of the insulating substrate; A base plate, one side surface of which is joined to the other side surface of the insulating substrate, and the other side surface of the base plate having a warped shape; as well as A heat sink abuts against the other side surface of the base plate. The heat sink is solid, and the shape of one side surface of the heat sink follows the warped shape of the base plate.

2. The semiconductor device as claimed in claim 1, characterized in that, The portion of the heat sink surface that abuts against the base plate is not adhesive.

3. The semiconductor device as claimed in claim 1, characterized in that, The portion of the heat sink surface that does not abut against the base plate is adhesive and is joined to the base plate side.

4. The semiconductor device as claimed in claim 1, characterized in that, The hardness of the heat sink, as measured by an E-type hardness tester, is in the range of 30 to 70 degrees.

5. The semiconductor device according to any one of claims 1 to 4, characterized in that, The heat sink has mounting holes in the portion that does not abut against the base plate, and the heat sink is fixed to the side of the base plate using the mounting holes.

6. The semiconductor device according to any one of claims 1 to 4, characterized in that, The other side surface of the heat sink is flat.

7. The semiconductor device according to any one of claims 1 to 4, characterized in that, The heat sink contains graphite as a component.

8. The semiconductor device according to any one of claims 1 to 4, characterized in that, The thickness of the heat sink varies depending on the warping of the base plate.

9. The semiconductor device according to any one of claims 1 to 4, characterized in that, The heat sink consists of two pieces of different thicknesses.

10. The semiconductor device according to any one of claims 1 to 4, characterized in that, The heat sink has multiple slits.

11. The semiconductor device according to any one of claims 1 to 4, characterized in that, The warped shape is a protruding warp whose height increases as it approaches the center.

12. The semiconductor device as claimed in claim 10, characterized in that, The warped shape is a warping with varying protrusion heights at different locations in the first direction. The plurality of slits are arranged in the first direction.

13. The semiconductor device as claimed in claim 10, characterized in that, The slit width of the plurality of slits increases as the protrusion height of the warped shape portion opposite to each slit increases.

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