Method for manufacturing a heat sink having fins and a peripheral sidewall

Abstract

A method for manufacturing a heat sink having fins and a peripheral side wall by means of extrusion. In order to save costs, the following steps are proposed: providing a female mold having a base surface and a male mold having a pressure surface, wherein the base surface of the female mold has an opening, wherein a peripheral recess is formed on the pressure surface of the male mold; placing a semi-finished product made of a first metal material into the female mold; detachably connecting a material layer made of a second metal material to the pressure surface of the male mold, the second metal material having a higher thermal conductivity than the first metal material; contacting the male mold via the material layer with the semi-finished product placed in the female mold; pressing the first metal material of the semi-finished product through the opening of the female mold by means of the male mold to form the fins and into the peripheral recess of the male mold to form the peripheral side wall, wherein the material layer is connected with the first metal material of the semi-finished product over the entire surface of the material layer, wherein the heat sink is formed by the pressing; detaching the male mold from the material layer; removing the heat sink from the female mold.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a radiator having fins and peripheral sidewalls by extrusion.

[0002] The present invention also relates to a heat sink for a semiconductor device, the heat sink being manufactured by such an extrusion process.

[0003] Furthermore, the present invention relates to a semiconductor device having at least one semiconductor element and a heat sink.

[0004] In addition, the present invention relates to a power converter having at least one semiconductor device. Background Technology

[0005] In such power converters, the semiconductor device is typically mounted to a heat sink. A power converter can be understood, for example, as a rectifier, inverter, converter, or DC-DC voltage converter. The semiconductor device is typically formed as an electronic module having a housing and screwed onto the heat sink via a solid metal base plate. Alternatively, the semiconductor device can be directly connected to the heat sink. The semiconductor device can include, but is not limited to, insulated-gate bipolar transistors (IGBTs) and / or metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0006] Publication EP 3 933 913 A1 describes a power module having at least two power units, each power unit comprising at least one power semiconductor and a substrate. To reduce the structural space required by the power module and improve heat dissipation, it is proposed that at least one power semiconductor conductor be connected to a corresponding substrate in a material-fit manner, wherein the substrates of the at least two power semiconductor units are directly connected to the surface of a common heat sink in a material-fit manner.

[0007] To meet the high insulation requirements in such electronic modules, potting compound is used to cover semiconductors and interconnects, such as bonding wires. The potting compound also prevents moisture penetration and component corrosion.

[0008] Publication WO 2021 / 058212 A1 describes a carrier for at least one electrical component. The carrier includes a radiator having a radiator surface and two sidewalls protruding from the radiator surface and facing each other, two spaced-apart sealing blocks disposed on the radiator surface, and a carrier structure for at least one electrical component disposed on the radiator surface between the two sealing blocks, the sealing blocks extending between the two sidewalls and abutting against each of the two sidewalls. Summary of the Invention

[0009] In this context, the object of the present invention is to provide a cost-effective method for manufacturing radiators.

[0010] According to the present invention, this objective is achieved by a method for manufacturing a heat sink having fins and peripheral sidewalls by extrusion, the method comprising the steps of: providing a female mold having a base surface and a male mold having a pressure surface, wherein the base surface of the female mold has an opening, and wherein a peripheral groove is formed on the pressure surface of the male mold; placing a semi-finished product made of a first metal material into the female mold; connecting a material layer made of a second metal material to the pressure surface of the male mold in a detachable manner, the second metal material having a higher thermal conductivity than the first metal material; contacting the male mold with the semi-finished product placed in the female mold via the material layer; pressing the first metal material of the semi-finished product through the opening of the female mold to form fins and pressing it into the peripheral groove of the male mold to form peripheral sidewalls by means of the male mold, wherein the material layer is connected to the first metal material of the semi-finished product with the entire surface of the material layer, wherein the heat sink is formed by pressing; separating the male mold from the material layer; and removing the heat sink from the female mold.

[0011] Furthermore, according to the invention, this objective is achieved by a heat sink for a semiconductor device, which is manufactured by such an extrusion process, the heat sink having: fins, which are manufactured by pressing a semi-finished product through an opening in a female mold by means of a pressure surface of a male mold; a peripheral sidewall, which is arranged on the side of the heat sink opposite to the fins and is manufactured by pressing a semi-finished product into a peripheral groove of the male mold; and a flat surface within the peripheral sidewall, which is formed by the pressure surface of the male mold and includes a material layer made of a second metallic material.

[0012] Furthermore, according to the invention, this objective is achieved by a semiconductor device having at least one semiconductor element and such a heat sink, wherein the semiconductor element is connected to the heat sink in an electrically insulating and thermally conductive manner.

[0013] Furthermore, according to the present invention, this objective is achieved by a power converter having at least one such semiconductor device.

[0014] The advantages of this method and the preferred design schemes listed below can be applied to heat sinks, semiconductor devices, and power converters.

[0015] This invention is based on the consideration that an improved cost position can be achieved by extruding a heat sink with peripheral sidewalls, fins, and a heat diffusion surface. The heat sink is manufactured using a semi-finished product made of a first metallic material. For example, the first metallic material is an aluminum alloy, particularly a forged aluminum alloy. The heat diffusion surface is manufactured using a material layer made of a second metallic material, which has a higher thermal conductivity than the first metallic material. The second metallic material is, for example, copper or a copper alloy. For example, the material layer is designed as a copper sheet.

[0016] The extrusion process is performed using a female die with a base surface and a male die with a pressure surface. Depending on the desired shape of the radiator, the base surface of the female die can be designed in a rectangular (especially square) or elliptical (especially circular) shape and have an opening. The opening can be, but is not limited to, rectangular, especially square, or elliptical, especially circular. A peripheral groove is formed on the pressure surface of the male die, which is manufactured, for example, by a cutting method, especially by milling. The groove is formed, for example, as a stepped groove with a rectangular or trapezoidal contoured portion.

[0017] The material layer is detachably attached to the pressure surface of the male mold. This detachable connection can be achieved, for example, by means of a detachable adhesive. This detachable adhesive connection of the material layer advantageously prevents displacement during the pressing process. After a semi-finished product made of a first metal material is placed into the female mold, the male mold contacts the semi-finished product placed in the female mold via the material layer. Then, the first metal material of the semi-finished product is pressed through an opening in the female mold by means of the male mold to form fins and pressed into a peripheral groove in the male mold to form peripheral sidewalls, wherein the material layer is connected to the first metal material of the semi-finished product with its entire surface to form a heat diffusion surface. The radiator is formed by the pressing process. This process is carried out, for example, by means of cup extrusion, particularly by means of forward cup extrusion. In another step, the male mold is detached from the material layer, and the radiator is removed from the female mold. After extrusion, no further steps are required, such as connecting the material layer to diffuse heat, thus saving costs even for small production runs.

[0018] Another embodiment proposes that, after pressing, the fins are cut to a certain length, particularly flush, in the die. Directly after extrusion, the fins can have different lengths and / or protrude irregularly from the opening in the die. By cutting, for example by means of sawing, milling, and / or cutting equipment, the fins are cost-effectively shortened to a uniform final length.

[0019] Another embodiment proposes that the material layer and the male mold be connected in a detachable manner, such that the material layer and the pressure surface of the male mold are flush. This arrangement allows for the cost-effective fabrication of the largest possible heat-diffusing surface.

[0020] Another embodiment proposes that the material layer be bonded to the first metal material via pressure welding in a material-fit manner. Such a connection can be manufactured robustly and cost-effectively. Furthermore, the thermal resistance between the second metal material and the first metal material of the material layer is reduced, particularly compared to welding or sintering connections.

[0021] Another embodiment proposes roughening the material layer on the side facing away from the pressure surface of the male mold. Such a roughened surface can be manufactured cost-effectively and improves the interlocking between the second and first metal materials in the material layer.

[0022] Another embodiment proposes that the material layer is connected to the first metallic material via micro-interlocks. In particular, roughened surfaces can be robustly and cost-effectively connected via micro-interlocks.

[0023] Another embodiment proposes that the opening of the female mold is formed as an elongated hole, wherein a semi-finished first metal material is pressed through the elongated hole of the female mold to form layered fins. The elongated hole can be formed in an angular or rounded shape. Optimal heat dissipation can be achieved, especially in the case of lateral cooling fluid flow, through the layered fins.

[0024] Another embodiment proposes that a dielectric material layer is detachably connected between the pressure surface of the male mold and a material layer made of a second metallic material, wherein the dielectric material layer is non-detachably connected to the material layer during pressing. The dielectric material layer comprises, for example, an organic insulator. The organic insulator can be, but is not limited to, filled with a ceramic material, such as alumina and / or aluminum nitride. The dielectric material layer is cost-effectively and simply pressed to the material layer by the pressure of the male mold.

[0025] Another embodiment proposes that the female mold has an inner shell surface and the male mold has an outer shell surface, wherein the outer shell surface of the male mold moves parallel to and flush with the inner shell surface of the female mold during pressing. This avoids post-processing of the heat sink, saving additional costs.

[0026] Another embodiment proposes using aluminum alloys, particularly forged aluminum alloys, as the first metallic material. This alloy possesses exceptional ductility, enabling the production of fins with a high length-to-spacing ratio, thereby improving cooling performance.

[0027] Another embodiment proposes using an aluminum alloy containing silicon in the range of 0.1% to 1% by weight, particularly 0.1% to 0.5%. The aluminum alloy can be, but is not limited to, EN AW 6060 (AlMgSi0.5). In the case of heat sinks manufactured by extrusion, especially compared to cast heat sinks, it is possible to use aluminum alloys with such a low silicon content, which leads to improved thermal conductivity. Attached Figure Description

[0028] The present invention will now be described and explained in more detail with reference to the embodiments shown in the accompanying drawings.

[0029] The attached diagram shows:

[0030] Figure 1 A schematic three-dimensional cross-sectional view showing a method for manufacturing a heat sink;

[0031] Figure 2 A schematic three-dimensional cross-sectional view showing another method step for manufacturing a heat sink is provided.

[0032] Figure 3 A schematic three-dimensional view of a heat sink with cylindrical fins is shown.

[0033] Figure 4 A schematic cross-sectional view showing additional process steps for manufacturing the heat sink is provided.

[0034] Figure 5 A schematic cross-sectional view of a heat sink with a dielectric material layer is shown.

[0035] Figure 6 A top view schematic diagram of a female mold with an opening formed as a rectangular elongated hole is shown.

[0036] Figure 7 A top view schematic diagram of a female mold having an opening formed as a rounded elongated hole is shown.

[0037] Figure 8 A schematic three-dimensional view of a heat sink with layered fins is shown.

[0038] Figure 9 A schematic cross-sectional view of a semiconductor device with a heat sink is shown.

[0039] Figure 10 A schematic diagram of a power converter is shown.

[0040] The embodiments explained below are preferred embodiments of the present invention. In the embodiments, the components described in the embodiments are various features of the present invention that can be considered independently of each other, and these features also independently improve the present invention and can be considered as part of the present invention individually or in combinations different from the combinations shown. Furthermore, the described embodiments can also be supplemented by other features among the features already described in the present invention.

[0041] The same reference numerals have the same meaning in different figures. Detailed Implementation

[0042] Figure 1A schematic three-dimensional cross-sectional view of a method for manufacturing a heat sink 2 by extrusion is shown. The heat sink 2 is manufactured by a forward extrusion process, particularly by a cup forward extrusion process. The method includes providing a female die 4 and a male die 8, the female die having a base surface 6 and the male die having a pressure surface 10. The base surface 6 of the female die 4 has, for example, a circular opening 12 for forming cylindrical cooling fins. A peripheral groove 14, particularly a stepped groove, is formed on the pressure surface 10 of the male die 8. Furthermore, the female die 4 has an inner shell surface 16, and the male die 8 has an outer shell surface 18, wherein the dimensions of the outer shell surface 18 of the male die 8 are designed such that the outer shell surface can move parallel to the inner shell surface 16 of the female die 4. In addition, a semi-finished product 20 is made from a first metal material and a material layer 22 is made from a second metal material. The second metal material has a higher thermal conductivity than the first metal material. For example, the first metal material is an aluminum alloy, particularly a forged aluminum alloy, which has a silicon content of less than 1% by weight, particularly less than 0.5%. The first metallic material can be, but is not limited to, EN AW 6060 (AlMgSi0.5). The second metallic material is, for example, copper or a copper alloy. For example, material layer 22 is designed as a copper sheet.

[0043] In another step, a semi-finished product 20 made of a first metal material is placed into the female mold 4 (B). The semi-finished product 20 is designed, for example, in a cuboid shape and adapted to the inner shell surface 16 of the female mold 4. Additionally, a material layer 22 made of a second metal material is detachably connected to the pressure surface 10 of the male mold 8 (C). This detachable connection can be established, for example, adhesively using a detachable adhesive. Alternatively, the material layer 22 can be detachably connected to the semi-finished product 20. The detachable connection between the material layer 22 and the semi-finished product 20 can also include placing the material layer 22 onto a particularly flat surface of the cuboid semi-finished product 20. The detachable adhesive connection of the material layer 22 prevents displacement during the pressing process.

[0044] In another step, the male mold 8 comes into contact with the semi-finished product 20 placed in the female mold 4 via the material layer 22. Specifically, the material layer 22 contacts the surface of the cuboid semi-finished product 20 with its entire surface.

[0045] Then, the semi-finished product 20 is pressed E by means of the male mold 8 to form the heat sink 2. The first metal material of the semi-finished product 20 is pressed through the opening 12 of the female mold 4 to form fins 24 and pressed into the peripheral groove 14 of the male mold 6 to form the peripheral sidewall 26. The material layer 22 is roughened on the side opposite to the pressure surface 10 of the male mold 8. By means of the pressure generated during the pressing process, the roughened material layer 22 is connected to the first metal material with the entire surface of the material layer via micro-interlocking. Additionally or alternatively, the connection is performed by means of pressure welding in a material-fit manner.

[0046] Figure 2 A schematic three-dimensional cross-sectional view is shown, illustrating another method step for manufacturing the heat sink 2, which includes removing the male mold 8 from the material layer 22 and removing the heat sink 2 from the female mold 4. For clarity, Figure 2 The extraction mechanism is not shown. Figure 2 Another design scheme of the method in the middle corresponds to Figure 1 The design scheme in the middle.

[0047] Figure 3 A schematic three-dimensional view of a heat sink 2 with cylindrical fins 24 is shown. A material layer 22 comprises copper and forms flat contact surfaces 28, for example rectangular surfaces, for contacting, particularly planar contacting, electronic devices such as power semiconductors. Thermal diffusion is achieved through the material layer 22 during operation of the electronic devices. Figure 3 Another design scheme for radiator 2 corresponds to Figure 2 The design scheme in the middle.

[0048] Figure 4 A schematic cross-sectional view shows additional method steps for manufacturing the heat sink 2. Figure 1 After pressing E as shown, the fins 24 are cut to a certain length H in the female mold 4. For example, the fins 24 are shortened to a uniform final length by means of a cutting mechanism 30. The cutting mechanism 30 may include a sawing device, a milling device, and / or a cutting device. Then, the male mold 8 is separated from the material layer 22 F, and the heat sink 2 is removed from the female mold 4 by a removal mechanism 32, which includes an ejector pin 34 corresponding to the fins 24. Figure 4 Another design scheme of the method in the middle corresponds to Figure 1 The design scheme in the middle.

[0049] Figure 5 A schematic cross-sectional view of a heat sink 2 with a dielectric material layer 36 is shown, which comprises, for example, an organic insulator. The organic insulator can be, but is not limited to, filled with a ceramic material, such as alumina and / or aluminum nitride. During the manufacture of the heat sink 2, the dielectric material layer 36 is detachably attached between the pressure surface 10 of the male mold 8 and the material layer 22. During pressing (E), the dielectric material layer 36 is then pressed against the material layer 22. Additionally, the heat sink 2 has layered fins 24. Figure 3 Another design scheme for radiator 2 corresponds to Figure 3 The design scheme in the middle.

[0050] Figure 6 A top view schematic diagram of a female mold 4 with an opening 12 formed as a rectangular elongated hole 38 is shown. Layered fins can be manufactured through these elongated holes 38. The rectangular elongated holes 38 are arranged in parallel and have the same spacing d. The spacing d can be varied to achieve concentrated heat dissipation, especially to avoid hot spots. Figure 6 Another design scheme for opening 12 in the middle corresponds to Figure 1 The design scheme in the middle.

[0051] Figure 7 A top view of a female mold 4 showing an opening 12 formed as a rounded elongated hole 40 is shown. For example, the opening 12 is designed as a semi-circular rounded elongated hole 40. Figure 7 Another design scheme for opening 12 in the middle corresponds to Figure 6 The design scheme in the middle.

[0052] Figure 8 A schematic three-dimensional view of a heat sink 2 with layered fins 24 is shown, the fins extending parallel and having the same spacing d. Specifically, the heat sink 2 uses... Figure 6 The female mold 4 is manufactured in the middle. The cooling fluid flow K extends along the parallel layered fins 24. Figure 8 Another design scheme for radiator 2 corresponds to Figure 3 The design scheme in the middle.

[0053] Figure 9 A schematic cross-sectional view of a semiconductor device 42 with a heat sink 2 is shown. The semiconductor device 42 includes, for example, a semiconductor element 44 formed as a vertical power transistor, particularly an insulated gate bipolar transistor (IGBT). The IGBT is connected, in particular, to a structured metallization 46 via a material-fitted connection, which is electrically insulating and thermally conductive to the heat sink 2 via a dielectric layer 36. For example, the IGBT is connected to the metallization 46 on the collector side via a material-fitted connection. The material-fitted connection can be, but is not limited to, a soldered connection and / or a sintered connection, and can also be an adhesive connection, for example, using a conductive and thermally conductive adhesive. Furthermore, the IGBT is connected to the metallization 46 on the gate side and emitter side via bonding connections 48, particularly via bonding wires or bonding strips. The semiconductor element 44 is completely encapsulated by a potting compound 50, which is defined by the peripheral sidewall 26 of the heat sink 2. The potting compound 50 includes, for example, a soft potting compound, particularly a silicone potting compound. Figure 9 Another design scheme for radiator 2 corresponds to Figure 8 The design scheme in the middle.

[0054] Figure 10 A schematic diagram of a power converter 52 is shown, which includes, for example, a semiconductor device 42 having a heat sink 2. Figure 10 Semiconductor device 42 in Figure 9 It forms as shown in the diagram.

[0055] In summary, the present invention relates to a method for manufacturing a radiator 2 having fins 24 and peripheral sidewalls 26 by extrusion. To save costs, the following steps are proposed: A. A female mold 4 with a base surface 6 and a male mold 8 with a pressure surface 10 are provided, wherein the base surface 6 of the female mold 4 has an opening 12, and a peripheral groove 14 is formed on the pressure surface 10 of the male mold 8; B. A semi-finished product 20 made of a first metal material is placed into the female mold 4; C. A material layer 22 made of a second metal material is connected to the pressure surface 10 of the male mold 8 in a detachable manner, wherein the second metal material has a higher thermal conductivity than the first metal material; D. The male mold 8 is brought into contact with the semi-finished product 20 placed in the female mold 4 via the material layer 22; E. The first metal material of the semi-finished product 20 is pressed through the opening 12 of the female mold 4 by means of the male mold 8 to form fins 24 and is pressed into the peripheral groove 14 of the male mold 8 to form a peripheral sidewall 26, wherein the material layer 22 is connected to the first metal material of the semi-finished product 20 with the entire surface of the material layer, wherein a heat sink 2 is formed by pressing E; F. The male mold 8 is detached from the material layer 22; G. The heat sink 2 is removed from the female mold 4.

Claims

1. A method for manufacturing a radiator (2) by extrusion, the radiator having fins (24) and peripheral sidewalls (26), the method comprising the steps of: - Provide (A) a female mold (4) having a base surface (6) and a male mold (8) having a pressure surface (10), wherein the base surface (6) of the female mold (4) has an opening (12), wherein a peripheral groove (14) is formed on the pressure surface (10) of the male mold (8). - The semi-finished product (20) made of the first metal material is placed into the female mold (4) described in (B); - A material layer (22) made of a second metal material is connected to the pressure surface (10) of the male mold (8) in a detachable manner (C), wherein the second metal material has a higher thermal conductivity than the first metal material; -The male mold (8) is brought into contact with the semi-finished product (20) placed in the female mold (4) via the material layer (22) (D); - The first metal material of the semi-finished product (20) is pressed (E) through the opening (12) of the female mold (4) by means of the male mold (8) to form the fins (24), and the first metal material of the semi-finished product is pressed into the peripheral groove (14) of the male mold (8) to form the peripheral sidewall (26), wherein the material layer (22) is connected to the first metal material of the semi-finished product (20) with the entire surface of the material layer, wherein the heat sink (2) is formed by the pressing (E); - Remove the male mold (8) from the material layer (22) (F); - Remove the heat sink (2) from the female mold (4) (G).

2. The method according to claim 1, wherein, After the pressing (E), the fins (24) are cut to a certain length (H) in the female mold (4).

3. The method according to claim 2, wherein, After the pressing (E), the fins (24) are cut flush to a certain length in the female mold (4).

4. The method according to any one of claims 1 to 3, wherein, The material layer (22) is connected to the male mold (8) in a detachable manner, such that the material layer (22) is flush with the pressure surface (10) of the male mold (8).

5. The method according to any one of claims 1 to 3, wherein, The material layer (22) is connected to the first metal material by pressure welding in a material-fit manner.

6. The method according to any one of claims 1 to 3, wherein, The material layer (22) is roughened on the side opposite to the pressure surface (10) of the male mold (8).

7. The method according to claim 6, wherein, The material layer (22) is connected to the first metal material via a micro-interlock.

8. The method according to any one of claims 1 to 3, wherein, The opening (12) of the female mold (4) is configured as an elongated hole (38, 40), wherein the first metal material of the semi-finished product (20) is pressed through the elongated hole (38, 40) of the female mold (4) to form layered fins (24).

9. The method according to any one of claims 1 to 3, wherein, A dielectric material layer (36) is detachably connected between the pressure surface (10) of the male mold (8) and the material layer (22) made of the second metal material, wherein the dielectric material layer (36) is non-detachably connected to the material layer (22) during the pressing (E).

10. The method according to any one of claims 1 to 3, wherein, The female mold (4) has an inner shell surface (16) and the male mold (8) has an outer shell surface (18), wherein the outer shell surface (18) of the male mold (8) moves parallel to the inner shell surface (16) of the female mold (4) during the pressing (E).

11. The method according to any one of claims 1 to 3, wherein, An aluminum alloy is used as the first metallic material.

12. The method according to claim 11, wherein, Forged aluminum alloy is used as the first metal material.

13. The method according to claim 11, wherein, Use aluminum alloys containing silicon in the range of 0.1% to 1% by weight.

14. The method according to claim 13, wherein, Use aluminum alloys containing silicon in the range of 0.1% to 0.5% by weight.

15. A heat sink (2) for a semiconductor device (42), said heat sink being manufactured by the method according to any one of the preceding claims, said heat sink having: - The fins (24) are manufactured by pressing (E) the semi-finished product (20) through the opening (12) of the female mold (4) using the pressure surface (10) of the male mold (8). - Peripheral sidewall (26), which is arranged on the side of the radiator (2) opposite to the fins (24) and is manufactured by pressing (E) the semi-finished product (20) into the peripheral groove (14) of the male mold (8). - A flat surface within the outer sidewall (26), the flat surface being formed by the pressure surface (10) of the male mold (8) and the flat surface forming a material layer (22) made of a second metallic material.

16. A semiconductor device (42) having at least one semiconductor element (44) and a heat sink (2) according to claim 15, wherein, The semiconductor element (44) is connected to the heat sink (2) in an electrically insulating and thermally conductive manner.

17. The semiconductor device (42) according to claim 16, wherein, At least one of the semiconductor elements (44) is encapsulated in a potting compound (50), wherein the potting compound (50) is defined by the peripheral sidewall (26) of the heat sink (2).

18. A power converter (52) having at least one semiconductor device (42) according to any one of claims 16 or 17.

Images