Semiconductor equipment

Abstract

The present invention provides a heat dissipation sheet and a semiconductor device that improve heat dissipation efficiency by forming a heat dissipation sheet along the curvature of the base plate and increasing the contact area with the base plate. [Solution] The semiconductor device 1 comprises an insulating substrate 2, a semiconductor element 7 bonded to one side of the insulating substrate, a base plate 3 having one side bonded to the other side of the insulating substrate and having a curve on the other side, and a heat dissipation sheet 16 in contact with the other side of the base plate. The heat dissipation sheet is made of solid material, and one side of the heat dissipation sheet has a shape that conforms to the curved shape of the base plate.

Description

Technical Field

[0001] The present disclosure relates to a semiconductor device.

Background Art

[0002] For example, Patent Document 1 discloses a device characterized by including a bonding layer containing a thermocompression bonding type adhesive between at least one of a semiconductor module and a heat dissipation sheet and between a cooling device provided on a surface of the heat dissipation sheet opposite to the semiconductor module.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the prior art described above, there is a case where the heat dissipation sheet cannot sufficiently follow the warpage of the base plate on the back surface of the semiconductor module, and the contact area between the heat dissipation sheet and the base plate is not sufficient with respect to the area of the base plate, resulting in a problem that the heat dissipation path is biased and heat cannot be sufficiently transferred to the fins.

[0005] Therefore, an object of the present disclosure is to provide a heat dissipation sheet capable of improving heat dissipation efficiency by increasing the contact area between a warped base plate and the heat dissipation sheet.

Means for Solving the Problems

[0006] The semiconductor device according to the present disclosure an insulating substrate, a semiconductor element bonded to one surface of the insulating substrate, a base plate having one surface bonded to the other surface of the insulating substrate and having a warp on the other surface, The base plate comprises a heat dissipation sheet in contact with the other side of the base plate, The heat dissipation sheet is solid, and one side of the heat dissipation sheet has a shape that conforms to the curvature of the base plate. [Effects of the Invention]

[0007] According to the semiconductor device described herein, by forming a heat dissipation sheet along the curvature of the base plate and increasing the contact area with the base plate, it is possible to improve heat dissipation efficiency. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view of the semiconductor device according to Embodiment 1. [Figure 2] This is a cross-sectional view of the semiconductor device according to Embodiment 1. [Figure 3] This is a bottom view of the heat dissipation sheet in a semiconductor device according to a modified example of Embodiment 1. [Figure 4] This is a cross-sectional view of the semiconductor device according to Embodiment 2. [Figure 5] This is a bottom view of the heat dissipation sheet in the semiconductor device according to Embodiment 2. [Modes for carrying out the invention]

[0009] 1. Embodiment 1 A semiconductor device 1 according to Embodiment 1 will be described with reference to the drawings. Figure 1 is a cross-sectional view of the semiconductor device 1 according to Embodiment 1. Figure 2 is a cross-sectional view of the semiconductor device 1 according to Embodiment 1. Figure 3 is a bottom view of the heat dissipation sheet 16 in a modified semiconductor device 1 according to Embodiment 1.

[0010] 1-1. Configuration of Semiconductor Device 1 The semiconductor device 1 comprises an insulating substrate 2, a semiconductor element 7 bonded to one side of the insulating substrate 2, a base plate 3 having one side bonded to the other side of the insulating substrate 2 and having a curve on the other side, and a heat dissipation sheet 16 in contact with the other side of the base plate 3. The heat dissipation sheet 16 is made of solid material, and one side of the heat dissipation sheet 16 has a shape that conforms to the curved shape of the base plate 3.

[0011] In this disclosure, the direction perpendicular to the direction in which the base plate 3 and the heat dissipation sheet 16 are joined is defined as the first direction.

[0012] <Insulating substrate 2> In this embodiment, the insulating substrate 2 has a semiconductor element 7 bonded to one side and a base plate 3 bonded to the other side, and is made of ceramic, resin, or the like. A bonding material 4 such as solder is used to bond the insulating substrate 2, the base plate 3, and the semiconductor element 7. A circuit pattern is created on the insulating substrate 2. For example, the circuit pattern is created by etching copper or the like.

[0013] For example, an insulating substrate consists of a circuit board and an insulating substrate. The insulating substrate is stacked in the order of circuit board, insulating substrate, circuit board, with the insulating substrate sandwiched between the two circuit boards. The circuit board is mainly made of copper and has a circuit pattern formed on it. The insulating substrate is made of an insulating ceramic material such as alumina. By sandwiching an insulator between the two types of circuit boards, the electrical circuits formed by the two types of circuit boards do not interfere with each other, preventing short circuits and electrical problems.

[0014] Bonding material is provided on both sides of the insulating substrate (one side of the circuit board on one side and the other side of the circuit board on the other side). Solder is mainly used as the bonding material, but a sintered material using a metal paste such as silver paste may also be used. A semiconductor element or capacitor chip is attached to one side of the insulating substrate where the bonding material is provided, and a heat sink is attached to the other side where the bonding material is provided.

[0015] A plurality of insulating substrates are connected to each other via bonding wires. The ends of the bonding wires are attached to one side surface of each insulating substrate so as to be connected to a circuit board.

[0016] <Semiconductor element 7> The semiconductor element 7 of the present embodiment is joined to one side surface of a circuit pattern formed on the insulating substrate 2. The semiconductor element 7 is, for example, an IGBT (Insulated Gate Bipolar Transistor) or a Diode. The semiconductor element 7 is connected to an electrode terminal attached to a case using a wire. For example, copper or aluminum is used for the wire.

[0017] For example, the semiconductor element is joined to one side surface of the insulating substrate. The other side surface of the semiconductor element is attached to one side surface of the above-described insulating substrate via a bonding material.

[0018] One end of a bonding wire is joined to one side surface of the semiconductor element. The other end of the bonding wire is joined to an external terminal. The semiconductor element is electrically connected to the outside by the bonding wire.

[0019] In the semiconductor element of this example, an IGBT is used. The IGBT is used for high voltage and high current switching and is utilized in motor control and inverter circuits, etc. The type of the semiconductor element may be not only an IGBT but also types such as a MOSFET.

[0020] <Base plate 3> In the present embodiment, the other side surface of the insulating substrate 2 is joined to one side surface of the base plate 3. The base plate 3 has a warp on the other side surface. Copper or aluminum is mainly used for the base plate 3. In the present embodiment, the warp is a convex warp in which the protruding height increases as it approaches the center portion. The other side surface of the base plate 3 has a convex spherical warp. Note that the warp may be a convex warp in which the protruding height increases as it approaches the center portion in a specific first direction as in Embodiment 2. In this case, the other side surface of the base plate 3 has a cylindrical spherical warp.

[0021] <Other components of semiconductor device 1> The semiconductor device 1 in this embodiment is enclosed by a resin case 11. The resin case 11 is a roughly rectangular box shape. It has a structure that can house the insulating substrate 2 and the semiconductor element 7 inside, and even if a liquid encapsulant 13 is poured into the resin case 11, it will not leak out to the outside. The resin case 11 is made of a resin such as PPS (polyphenylene sulfide). Other resins may be used instead of PPS (polyphenylene sulfide).

[0022] As described above, one end of a bonding wire 12 is attached to a portion of one side 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 is in contact with an external terminal 8, which extends along the inner surface of the resin case 11, and the other end of the external terminal 8 is exposed to the outside from the resin case 11 and the sealing material 13. The external terminal 8, which is exposed to the outside, can be connected to other components by coming into contact with them.

[0023] The semiconductor element 7, insulating substrate 2, and bonding wire 12 are enclosed by a resin case 11 and a base plate 3. A sealing material 13 is filled inside the resin case 11 and the heat sink, protecting the semiconductor element 7, insulating substrate 2, etc.

[0024] <Heat dissipation sheet 16> In this embodiment, the heat dissipation sheet 16 is in contact with the other side surface of the base plate 3. The heat dissipation sheet 16 is solid, and one side surface of the heat dissipation sheet 16 has a shape that conforms to the curvature of the base plate 3. This configuration allows the heat dissipation sheet 16 to make sufficient contact with the area of ​​the other side surface of the base plate 3. Sufficient contact makes it possible to efficiently dissipate the heat from the base plate 3 via the heat dissipation sheet 16. The dissipated heat is transferred to the fins, which are coolers 9, attached to the other side surface of the heat dissipation sheet 16, and the semiconductor device 1 is cooled. When the heat dissipation sheet 16 and the base plate 3 are separated, one side surface of the heat dissipation sheet 16 maintains its shape that conforms to the curvature of the base plate 3.

[0025] In this embodiment, the heat dissipation sheet 16 does not have adhesive properties on one side that is in contact with the base plate 3. This configuration makes it possible to reduce the effect of heat dissipation by placing the adhesive portion on the resin case 11 rather than on the base plate 3 exposed on the other side of the semiconductor device 1.

[0026] In this embodiment, the heat dissipation sheet 16 has adhesive properties on one side that is not in contact with the base plate 3, and is bonded to the base plate 3 side (in this example, the resin case 11). Since the semiconductor device 1 is hottest directly beneath the semiconductor element 7, efficiently dissipating the heat directly beneath the semiconductor element 7 is important for cooling the semiconductor device 1. Therefore, in this embodiment, the bonding portion, which has lower thermal conductivity than the heat dissipation sheet 16, is positioned to avoid the base plate 3 located directly beneath the semiconductor element 7. This configuration makes it possible to increase the heat dissipation efficiency.

[0027] In this embodiment, the heat dissipation sheet 16 has mounting holes 17 in the portion not in contact with the base plate 3, and is fixed to the base plate 3 side (in this example, the resin case 11) using the mounting holes 17. For example, fastening members such as screws or bolts are inserted through the mounting holes 17 to fix the heat dissipation sheet 16 to the resin case 11. This configuration makes it possible to attach the semiconductor device 1 to the cooler 9 with the heat dissipation sheet 16 bonded to it. As a result, it becomes possible to omit the positioning of the semiconductor device 1 and the heat dissipation sheet 16.

[0028] In this embodiment, the heat dissipation sheet 16 contains graphite as a component. Graphite has high thermal conductivity and is widely used as a material for the heat dissipation sheet 16. The heat dissipation sheet 16 is formed with a hardness in the range of 30 to 70 degrees of Type E hardness. This configuration makes it possible to increase the heat dissipation efficiency. Graphite has anisotropy in thermal conductivity, and a layer of graphite is provided vertically on the base plate 3. This configuration makes it possible to increase the thermal conductivity of the graphite. Graphite does not necessarily have anisotropy in thermal conductivity.

[0029] In this embodiment, the heat dissipation sheet 16 has different thicknesses depending on the curvature of the base plate 3. Furthermore, the thickness of the heat dissipation sheet 16 is reduced as the protrusion height of the other side of the base plate 3 increases. This configuration makes it possible to keep one side of the heat dissipation sheet 16 conform to the curvature while keeping the other side flat, and to join the other side of the heat dissipation sheet 16 when attaching the fins of the cooler 9 to the other side of the heat dissipation sheet 16.

[0030] In a modified version of this embodiment, the heat dissipation sheet 16 is composed of two sheets of different thicknesses. As shown in Figure 2, the first heat dissipation sheet 16a on the base plate 3 side and the second heat dissipation sheet 16b on the opposite side of the base plate 3 are superimposed. One side of the first heat dissipation sheet 16 has a shape that conforms to the curvature of the base plate 3, and the other side of the first heat dissipation sheet 16 is flat and is joined to one side of the second heat dissipation sheet 16. The second heat dissipation sheet 16 is formed in a flat plate shape and is larger than the first heat dissipation sheet 16. Since the heat dissipation sheet 16 is mainly composed of graphite, it is difficult to polish and difficult to create variations in thickness in a single sheet. This configuration makes it possible to easily process heat dissipation sheets 16 of different thicknesses. Alternatively, as shown in Figure 3, it may be composed of a first heat dissipation sheet 16a with a hole formed in the center and a second heat dissipation sheet 16b that fits into the shape of the hole. The second heat dissipation sheet 16b faces the base plate 3 and has a shape that conforms to the curvature of the base plate 3.

[0031] 2. Embodiment 2 A semiconductor device 1 according to Embodiment 2 will be described with reference to the drawings. Figure 4 is a cross-sectional view of the semiconductor device 1 according to Embodiment 2. Figure 5 is a bottom view of the heat dissipation sheet 16 in the semiconductor device 1 according to Embodiment 2.

[0032] The heat dissipation sheet 16 according to this embodiment has multiple slits. With this configuration, when the heat dissipation sheet 16 is pressed against the base plate 3, the width of the slits changes, which makes it easier for the thickness of the portion of the heat dissipation sheet 16 adjacent to the slits to change, and the heat sheet is more likely to deform along the convex curvature of the base plate 3. In addition, the larger contact surface makes it possible to increase the heat dissipation efficiency. The shape of the slits may be curved or polygonal.

[0033] In this embodiment, the curvature of the base plate 3 is a convex curvature in which the protrusion height increases as it approaches the center. The other side surface of the base plate 3 has a cylindrical spherical curvature. With this configuration, the base plate 3 of the semiconductor device 1 has a convex curvature in which the protrusion height is greatest at the center in the first direction. As with Embodiment 1, the other side surface of the base plate 3 may have a convex spherical curvature.

[0034] In this embodiment, the width of the slits increases as the protruding height of the curved portion opposite each slit increases. With this configuration, since the base plate 3 of the semiconductor device 1 has a convex curve with the largest protruding height in the center, widening the slit spacing in the center of the heat dissipation sheet 16 ensures space for the heat dissipation sheet 16 to spread into the slits in areas with large protruding heights and high pressing forces, making it easier to deform along the curve. The slit spacing narrows towards the edges of the base plate 3. This configuration makes it possible to reduce the gap between the heat dissipation sheet 16 and the base plate 3 in areas with small pressing forces and small deformations. Furthermore, reducing the gap makes it possible to increase the heat dissipation efficiency.

[0035] The curvature in this embodiment is a curvature in which the protrusion height differs at each position in the first direction, and the multiple slits are arranged in the first direction. With this configuration, by aligning the first direction in which the protrusion heights differ with the direction in which the multiple slits are arranged, it becomes easier to deform the heat dissipation sheet 16 in accordance with the difference in protrusion height at each position in the first direction.

[0036] If the height of the warp protrusion varies due to individual differences, the width of the multiple slits in each individual may be changed according to the variation in the protrusion height of each individual. That is, for each individual, the width of the slit may be changed according to the protrusion height of the warp portion facing each slit, such that the width of the slit increases as the protrusion height of the warp portion facing each slit increases. Even if individual differences occur where the protrusion height varies depending on the position, the heat dissipation sheet 16 can be appropriately deformed to conform to the warp of the base plate 3. [Explanation of symbols]

[0037] 1 Semiconductor device, 2 Insulating substrate, 3 Base plate, 4 Bonding material, 5 Circuit board, 7 Semiconductor element, 8 External terminals, 9 Cooler (fins), 11 Resin case, 12 Bonding wire, 13 Encapsulating material, 16 Heat dissipation sheet, 16a First heat dissipation sheet, 16b Second heat dissipation sheet, 17 Mounting holes

Claims

1. Insulating substrate and A semiconductor element bonded to one side of the insulating substrate, One side of the insulating substrate is joined to the other side of a base plate having a curved shape on the other side, The base plate comprises a heat dissipation sheet in contact with the other side of the base plate, The heat dissipation sheet is solid, and one side of the heat dissipation sheet has a shape that conforms to the curvature of the base plate.

2. The semiconductor device according to claim 1, wherein the heat dissipation sheet has no adhesive properties in the portion of one side that is in contact with the base plate.

3. The semiconductor device according to claim 1, wherein the heat dissipation sheet has adhesive properties in the portion of the surface that is not in contact with the base plate and is bonded to the base plate side.

4. The semiconductor device according to claim 1, wherein the heat dissipation sheet has a hardness measured by a hardness tester type E in the range of 30 to 70 degrees.

5. The semiconductor device according to any one of claims 1 to 4, wherein the heat dissipation sheet has mounting holes in the portion that is not in contact with the base plate, and is fixed to the base plate side using the mounting holes.

6. The semiconductor device according to any one of claims 1 to 4, wherein the heat dissipation sheet has a flat surface on the other side.

7. The semiconductor device according to any one of claims 1 to 4, wherein the heat dissipation sheet contains graphite as a component.

8. The semiconductor device according to any one of claims 1 to 4, wherein the heat dissipation sheet has a thickness that varies according to the curvature of the base plate.

9. The semiconductor device according to any one of claims 1 to 4, wherein the heat dissipation sheet is composed of two sheets of different thicknesses.

10. The heat dissipation sheet has a plurality of slits, according to any one of claims 1 to 4.

11. The semiconductor device according to any one of claims 1 to 4, wherein the aforementioned curvature is a convex curvature in which the protruding height increases as it approaches the center.

12. The aforementioned curvature is a curvature in which the protruding height differs at each position in the first direction. A semiconductor device according to any one of claims 1 to 4, wherein the plurality of slits are arranged in the first direction.

13. The semiconductor device according to claim 10, wherein the width of the slits increases as the protruding height of the curved portion facing each slit increases.

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