WO2023175122A1 - Multi-metal cooler and method for forming a multi-metal cooler - Google Patents

Multi-metal cooler and method for forming a multi-metal cooler Download PDF

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Publication number
WO2023175122A1
WO2023175122A1 PCT/EP2023/056839 EP2023056839W WO2023175122A1 WO 2023175122 A1 WO2023175122 A1 WO 2023175122A1 EP 2023056839 W EP2023056839 W EP 2023056839W WO 2023175122 A1 WO2023175122 A1 WO 2023175122A1
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WO
WIPO (PCT)
Prior art keywords
metal part
metal
cooler
materially bonded
mould
Prior art date
Application number
PCT/EP2023/056839
Other languages
French (fr)
Inventor
Michael Timmermann
Andre Staack
Karsten LUND
Ekkehard Handke
Original Assignee
Danfoss Silicon Power Gmbh
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Filing date
Publication date
Application filed by Danfoss Silicon Power Gmbh filed Critical Danfoss Silicon Power Gmbh
Publication of WO2023175122A1 publication Critical patent/WO2023175122A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H01L23/367—Cooling facilitated by shape of device
    • H01L23/3672—Foil-like cooling fins or heat sinks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
    • H01L21/4814—Conductive parts
    • H01L21/4871—Bases, plates or heatsinks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
    • H01L21/4814—Conductive parts
    • H01L21/4871—Bases, plates or heatsinks
    • H01L21/4882—Assembly of heatsink parts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon
    • H01L23/3736—Metallic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon
    • H01L23/3735—Laminates or multilayers, e.g. direct bond copper ceramic substrates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/46—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/46—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids
    • H01L23/467—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids by flowing gases, e.g. air
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/46—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids
    • H01L23/473—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids by flowing liquids

Definitions

  • the invention relates to a multi-metal cooler and a method for forming a multi-metal cooler.
  • a cooler attached to the electrical component in a thermal conducting manner takes away the heat from the electrical component.
  • the cooler may be a heat sink or a structure through which coolant passes.
  • Such coolers are often made of aluminium, since aluminium has a good thermal conductivity and may easily be formed into useful shapes. However, aluminium readily forms an aluminium oxide coating on its surface such that it is difficult to connect to aluminium in a reliable way using soldering, sintering, brazing or other commonly used connection techniques.
  • the technical object may be providing a method for forming a multi-metal cooler and a multi-metal cooler providing an improved reliability of the multi-metal connection and in improved thermal conductivity through the multi-metal connection.
  • Claims 1 and 8 indicate the main features of the invention.
  • Features of embodiments of the invention are subject of claims 2 to 7 and 9 to 11.
  • a method for forming a multi-metal cooler comprising the following steps: connecting at least one first metal part to at least one second metal part in a materially bonded manner; pressing the at least one first metal into the at least one second metal part after the step of connecting the at least one first metal part to the at least one second metal part in a materially bonded manner; and shaping the at least one second metal part into a predetermined shape of the multi-metal cooler.
  • the method provides a combination of pressing the first metal part into the second metal part after connecting the first and second metal parts materially bonded manner.
  • the connection in a materially bonded manner may also be called a substance-to-sub- stance bonded connection.
  • the materially bonded connection between the first metal part and the second metal part provides a reliable attachment of the first metal part to the second metal part.
  • the materially bonded connection provides an efficient thermal conductivity between the first metal part and the second metal part.
  • the second metal part may be shaped into a predetermined shape.
  • the predetermined shape may for example comprise cooling fins on a side being opposite to the first metal part.
  • the first metal part may for example comprise a contact surface for an element to be cooled.
  • the first metal part may for example be smaller than the second metal part. Then, the first metal part may just cover the area required for contacting an electrical component to be cooled.
  • the method provides a multi-metal cooler having an improved reliability of the multi-metal connection between the at least one first metal part and the at least one second metal part and in improved thermal conductivity through the multi-metal connection.
  • the steps of pressing the at least one first metal into the at least one second metal part and shaping the at least one second metal part into a predetermined shape may be performed simultaneously, preferably by using a moulding tool, particularly a forging press.
  • the at least one second metal part may be arranged in a structured mould with a side opposite the at least one metal part.
  • the structured mould may have structures for forming cooling fins.
  • the forging press may have a second mould to close the structured mould.
  • the second metal part When closing the structured mould with the second mould, the second metal part may be pressed into the structured mould such that the second metal part is shaped to the predetermined shape.
  • the first metal part being in materially bonding connection with the second metal part may be pressed into the second metal part.
  • the pressing and the shaping may be performed at the same time in one-step being very quick and cost efficient.
  • the step connecting at least one first metal part to at least one second metal part in a materially bonded manner may be performed by rolling the at least first metal part on the at least one second metal part and/or a subsequent thermal conditioning of the first and second metal part being attached to each other
  • the at least one first metal part may have the shape of a strip that is rolled onto the second metal part having the shape of a band.
  • Several strip-shaped first metal parts may be rolled on the second metal part or on a plurality of second metal parts. Rolling the first metal part on the second metal part may simplify the connection step.
  • the connection between the first metal part and the second metal part may be stronger than when simply pressing the first metal part into the second metal part.
  • At least one slug may be punched from the connected first and second metal parts.
  • the slug may be shaped to a multi-metal cooler in the step shaping the at least one second metal part into a predetermined shape of the multi-metal cooler.
  • an intermetallic phase between the at least one first metal part and the at least one second metal part is formed.
  • the material of both metal parts may mix, wherein the intermetallic phase is a chemical bonding between the two metals that may have a grid structure.
  • the intermetallic phase may be achieved by treating the contact surfaces to be of the first and second metal part before connecting them and by thermally conditioning the first and second metal part after connecting them.
  • the intermetallic phase comprising a thickness in the range from 5 pm to 40 pm, preferably in the range from 10 pm to 20 pm.
  • the at least one first metal part is made of copper and/or the at least one second metal part is made of aluminium.
  • the at least one first metal part is pressed into the at least one second metal part such that an outer surface of the at least one first metal part and an outer surface of the at least one second metal part are essentially arranged in a common plane.
  • the first metal part may protrude from the second metal part after connecting them. Then, the first metal part may be pressed into the second metal part until the surface of the first metal part facing away from the second metal part is flush with the adjacent surface of the second metal part. This simplifies processing those surfaces, e.g. for printing of sinter paste for connecting an electronic component to the first metal part.
  • a multi-metal cooler comprising at least one first metal part and at least a second metal part, wherein the at least one first metal part is connected to the at least one second metal part in a materially bonded manner and wherein the at least one second metal part defines the shape of the multi-metal cooler.
  • the connection between the at least one first metal part and the at least one second metal part comprises an intermetallic phase, preferably having a thickness in the range from 5 pm to 40 pm, further preferably in the range from 10 pm to 20 pm.
  • the at least one first metal part is made of copper and/or the at least one second metal part is made of aluminium.
  • a first outer surface of the at least one first metal part and a second outer surface of the at least one second metal part are essentially arranged in a common plane.
  • Fig. 1 a flow chart of the method for forming a multi-metal cooler
  • Fig. 2a-c a schematic drawing of three first metal parts connected to one second metal part
  • FIG. 3 a schematic drawing of a slug
  • Fig. 4a, b a schematic drawing of a mould forming a slug to a multi-metal cooler
  • Fig. 1 shows a flow chart of the method 100 for forming a multi-metal cooler.
  • step 102 at least one first metal part may be materially bonded to a second metal part.
  • the first metal part may be made of copper and the second metal part may be made of aluminium.
  • the contact surfaces to be of the first and second metal part may for example be brushed in step 114.
  • the brushing may for example, be performed by using a wire brush to increase the roughness of the contact surfaces and to reduce and/or remove a metal oxide layer on the surface to provide an improved connection of both metals.
  • the brush may have wires made of copper plated steel.
  • the brush may for example be a T-shaped wire brush or a bowl-shaped wire brush.
  • the wires may have a diameter in the range from 0.1 mm to 1 mm, preferably of 0.3 mm.
  • the rotation of the wire brushes may for example be in the range from 1000 rotations per minute to 100000 rotations per minute, further preferably in the range from 2000 rotations per minute to 50000 rotations per minute, most preferred 10000 rotations per minute.
  • Step 102 may for example comprise the sub-step 110, wherein the first metal part is rolled on the second metal part.
  • the first metal part may be a strip that is rolled on the second metal part being a band.
  • a plurality of first metal parts may be rolled on one or more bands of second metal parts.
  • the step of rolling the first metal part on the second metal part may be performed with predefined velocities and predefined pulling forces.
  • the velocity may for example be in the range from 0,015 meter per second to 1 ,5 meter per second, further preferably in the range from 0,1 meter per second to 0,3 meter per second, most preferred 0,15 meter per second.
  • the brushing strokes in step 114 may for example be performed in parallel to the rolling direction of the first metal part. This may increase the connection between the metal parts.
  • the first and second metal part may be thermally conditioned, for example, heated.
  • the thermal conditioning may cause the formation of an intermetallic phase at the contact surfaces of the first and second metal part.
  • the intermetallic phase may be arranged between the first metal part and the second metal part.
  • the intermetallic phase between the first and second metal part may also be formed in a different manner.
  • the intermetallic phase between the first and second metal part may comprise a thickness in the range from 5 pm to 40 pm, preferably in the range from 10 pm to 20 pm. If the intermetallic phase becomes too thick, the intermetallic phase may cause a decrease of the cooling performance of the multi-metal cooler.
  • three first metal parts 12 being strip-shaped may be rolled on a bandshaped second metal part 14.
  • the material bond in the form of the intermetallic phase 16 attaches each first metal part 12 to the second metal part 14.
  • the first metal parts 12 protrude from the second metal part 14.
  • a first outer surface 28 of the first metal part 12 faces away from the second metal part 14.
  • the second metal part 14 further comprises a second outer surface 30 being adjacent to the first metal parts 12.
  • slugs 18 may for example be punched, cut using waterjets or wire cutting / wire erosion techniques, from the combined first and second metal part as indicated in Fig. 2c. Each slug may then be formed to a multi-metal cooler in the further steps. By punching a plurality of slugs 18 from a combined first and second metal band, a high number of slugs 18 may be produced in a short time.
  • Fig. 3 shows a slug 18.
  • the slug 18 is a pre-shaped multi-metal cooler, thus most dimensions of the slug 18 are close to the dimensions of the future multi-metal cooler.
  • the slug 18 comprises three material islands formed by the first metal parts 12in the material of the second metal part 14.
  • the at least one first metal part being connected to the at least one second metal part is pressed into the at least one second metal part. If the first metal part is made of copper and the second metal part is made of aluminium, the first metal part is harder than the second metal part. Pressing the first metal part into the second metal part may therefore substantially only deform the second metal part.
  • the first outer surface of the first metal part facing away from the second metal part and the second outer surface of second metal part adjacent to the first outer surface may be flush to each other. That means that the first outer surface and the second outer surface may be substantially arranged in a common plane.
  • the first outer surface and the second outer surface may be seamlessly connected to each other or comprise a thin seam in the range of 10 pm to 100 pm.
  • the second metal part is shaped into a predetermined shape of a multi-metal cooler.
  • the predetermined shape may comprise cooling fins at a side being opposite to side connected to the first metal part.
  • Steps 104 and 106 may be carried out simultaneously in according to step 108.
  • the simultaneous pressing and shaping may for example be performed by using a moulding tool, particularly a forging press. This is shown in more detail in Figs. 4a and 4b.
  • the slug 18 is arranged on a structured mould 20 of a forging press.
  • the first metal parts 12 face out of the structured mould.
  • the structured mould 20 is only configured to shape the second metal part 14.
  • the structured mould 20 comprises structures 24 for forming cooling fins.
  • a second mould 22 of the forging press may be arranged on the first metal parts 12 as shown in Fig. 4a.
  • the slug 18 is sandwiched between the structured mould 20 and the second mould 22.
  • the second mould 22 presses the first metal parts 12 into the second metal part 14.
  • the material of the second metal part 14 may flow around the first metal parts 12 until the first outer surface 28 is flush to the second outer surface 30 as shown in Fig. 4b.
  • the material bonding between the first and second metal parts 12, 14 is pressed with the first metal part into the second metal part.
  • the second metal part 14 is pressed into the structured mould 20 to form a multi-metal cooler 10.
  • Cold forging may shape the second metal part 14. Due to the pressing force of the forging press, the material of the second metal part 14 flows into the structures 24 of the structured mould 20.
  • the structures 24 of the structures mould 20 may form cooling fins 26 for the multi-metal cooler 10 on the second metal part 14.
  • the forged multi-metal cooler 10 may be milled to receive a final shape of the multimetal cooler 10.
  • the first outer surfaces 28 may be the contact surfaces for electrical components to be cooled.
  • the heat of the electrical components may be conducted by the first metal part via the intermetallic phase 16 to the second metal part 14. Then, the cooling fins 26 of the multi-metal cooler 10 may dissipate the heat.
  • the structured mould 20 may comprise structures for forming cooling channels (not shown) for a cooling fluid in the second metal part.
  • first metal part 14 second metal part

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)

Abstract

The invention relates to a method (100) for forming a multi-metal cooler, the method (100) comprising the following steps: Connecting (102) at least one first metal part to at least one second metal part in a materially bonded manner Pressing (104) the at least one first metal into the at least one second metal part after the step of connecting the at least one first metal part to the at least one second metal part in a materially bonded manner; and Shaping (106) the at least one second metal part into a predetermined shape of the multi-metal cooler. The method (100) provides an improved reliability of the multi-metal connection and in improved thermal conductivity through the multi-metal connection of the formed multi-metal cooler.

Description

Multi-metal cooler and method for forming a multi-metal cooler
The invention relates to a multi-metal cooler and a method for forming a multi-metal cooler.
Electrical components like power modules require cooling. A cooler attached to the electrical component in a thermal conducting manner takes away the heat from the electrical component. The cooler may be a heat sink or a structure through which coolant passes. Such coolers are often made of aluminium, since aluminium has a good thermal conductivity and may easily be formed into useful shapes. However, aluminium readily forms an aluminium oxide coating on its surface such that it is difficult to connect to aluminium in a reliable way using soldering, sintering, brazing or other commonly used connection techniques.
It is known to add a layer of copper on top of the aluminium at the contact position of the electrical component to form a multi-metal cooler. Copper is much easier to connect to. Copper is also very good for heat spreading since it has a better thermal conductivity than aluminium. The electrical component may then be attached to the copper layer of the multi-metal cooler.
Thus, the technical object may be providing a method for forming a multi-metal cooler and a multi-metal cooler providing an improved reliability of the multi-metal connection and in improved thermal conductivity through the multi-metal connection.
Claims 1 and 8 indicate the main features of the invention. Features of embodiments of the invention are subject of claims 2 to 7 and 9 to 11.
In an aspect of the invention, a method for forming a multi-metal cooler is provided, comprising the following steps: connecting at least one first metal part to at least one second metal part in a materially bonded manner; pressing the at least one first metal into the at least one second metal part after the step of connecting the at least one first metal part to the at least one second metal part in a materially bonded manner; and shaping the at least one second metal part into a predetermined shape of the multi-metal cooler.
According to the invention, the method provides a combination of pressing the first metal part into the second metal part after connecting the first and second metal parts materially bonded manner. The connection in a materially bonded manner may also be called a substance-to-sub- stance bonded connection. The materially bonded connection between the first metal part and the second metal part provides a reliable attachment of the first metal part to the second metal part. Furthermore, the materially bonded connection provides an efficient thermal conductivity between the first metal part and the second metal part. By pressing the first metal part into the second metal part, the attachment of the first metal part to the second metal part is increased further. In addition, portions of the first metal part protruding from the second metal part may be pressed into the second metal part to create a substantially flat surface of the multi-metal cooler. The second metal part may be shaped into a predetermined shape. The predetermined shape may for example comprise cooling fins on a side being opposite to the first metal part. The first metal part may for example comprise a contact surface for an element to be cooled. Furthermore, the first metal part may for example be smaller than the second metal part. Then, the first metal part may just cover the area required for contacting an electrical component to be cooled. Hence, the method provides a multi-metal cooler having an improved reliability of the multi-metal connection between the at least one first metal part and the at least one second metal part and in improved thermal conductivity through the multi-metal connection.
In an example, the steps of pressing the at least one first metal into the at least one second metal part and shaping the at least one second metal part into a predetermined shape may be performed simultaneously, preferably by using a moulding tool, particularly a forging press.
This increases the time efficiency of manufacturing the multi-metal cooler. For example, if a forging press is used, the at least one second metal part may be arranged in a structured mould with a side opposite the at least one metal part. Thus, the side at which the at least one first metal part is arranged faces away from the mould. The structured mould may have structures for forming cooling fins. The forging press may have a second mould to close the structured mould. When closing the structured mould with the second mould, the second metal part may be pressed into the structured mould such that the second metal part is shaped to the predetermined shape. Simultaneously, the first metal part being in materially bonding connection with the second metal part may be pressed into the second metal part. Hence, the pressing and the shaping may be performed at the same time in one-step being very quick and cost efficient.
In an example, the step connecting at least one first metal part to at least one second metal part in a materially bonded manner may be performed by rolling the at least first metal part on the at least one second metal part and/or a subsequent thermal conditioning of the first and second metal part being attached to each other
For example, the at least one first metal part may have the shape of a strip that is rolled onto the second metal part having the shape of a band. Several strip-shaped first metal parts may be rolled on the second metal part or on a plurality of second metal parts. Rolling the first metal part on the second metal part may simplify the connection step. Furthermore, the connection between the first metal part and the second metal part may be stronger than when simply pressing the first metal part into the second metal part. At least one slug may be punched from the connected first and second metal parts. The slug may be shaped to a multi-metal cooler in the step shaping the at least one second metal part into a predetermined shape of the multi-metal cooler.
In an example, in the step connecting at least one first metal part to at least one second metal part in a materially bonded manner, an intermetallic phase between the at least one first metal part and the at least one second metal part is formed.
In the intermetallic phase between the first metal part and the second metal part, the material of both metal parts may mix, wherein the intermetallic phase is a chemical bonding between the two metals that may have a grid structure. The intermetallic phase may be achieved by treating the contact surfaces to be of the first and second metal part before connecting them and by thermally conditioning the first and second metal part after connecting them.
In an example, the intermetallic phase comprising a thickness in the range from 5 pm to 40 pm, preferably in the range from 10 pm to 20 pm.
In an example, the at least one first metal part is made of copper and/or the at least one second metal part is made of aluminium.
In an example, in the step of pressing the at least one first metal into the at least one second metal part, the at least one first metal part is pressed into the at least one second metal part such that an outer surface of the at least one first metal part and an outer surface of the at least one second metal part are essentially arranged in a common plane.
The first metal part may protrude from the second metal part after connecting them. Then, the first metal part may be pressed into the second metal part until the surface of the first metal part facing away from the second metal part is flush with the adjacent surface of the second metal part. This simplifies processing those surfaces, e.g. for printing of sinter paste for connecting an electronic component to the first metal part.
According to another aspect of the invention, a multi-metal cooler is provided comprising at least one first metal part and at least a second metal part, wherein the at least one first metal part is connected to the at least one second metal part in a materially bonded manner and wherein the at least one second metal part defines the shape of the multi-metal cooler. In an example, the connection between the at least one first metal part and the at least one second metal part comprises an intermetallic phase, preferably having a thickness in the range from 5 pm to 40 pm, further preferably in the range from 10 pm to 20 pm.
In an example, the at least one first metal part is made of copper and/or the at least one second metal part is made of aluminium.
In an example, a first outer surface of the at least one first metal part and a second outer surface of the at least one second metal part are essentially arranged in a common plane.
The effects and further embodiments of the multi-metal cooler according to the present invention are analogous to the effects and embodiments of the method according to the description mentioned above. Thus, it is referred to the above description of the method.
Further features, details and advantages of the invention result from the wording of the claims as well as from the following description of exemplary embodiments based on the drawings. The figures show:
Fig. 1 a flow chart of the method for forming a multi-metal cooler;
Fig. 2a-c a schematic drawing of three first metal parts connected to one second metal part;
Fig. 3 a schematic drawing of a slug; and
Fig. 4a, b a schematic drawing of a mould forming a slug to a multi-metal cooler
Fig. 1 shows a flow chart of the method 100 for forming a multi-metal cooler.
In step 102, at least one first metal part may be materially bonded to a second metal part. The first metal part may be made of copper and the second metal part may be made of aluminium. As preparation of step 102, the contact surfaces to be of the first and second metal part may for example be brushed in step 114.
The brushing may for example, be performed by using a wire brush to increase the roughness of the contact surfaces and to reduce and/or remove a metal oxide layer on the surface to provide an improved connection of both metals. For example, the brush may have wires made of copper plated steel. The brush may for example be a T-shaped wire brush or a bowl-shaped wire brush. The wires may have a diameter in the range from 0.1 mm to 1 mm, preferably of 0.3 mm. The rotation of the wire brushes may for example be in the range from 1000 rotations per minute to 100000 rotations per minute, further preferably in the range from 2000 rotations per minute to 50000 rotations per minute, most preferred 10000 rotations per minute.
Step 102 may for example comprise the sub-step 110, wherein the first metal part is rolled on the second metal part. The first metal part may be a strip that is rolled on the second metal part being a band. A plurality of first metal parts may be rolled on one or more bands of second metal parts.
The step of rolling the first metal part on the second metal part may be performed with predefined velocities and predefined pulling forces. The velocity may for example be in the range from 0,015 meter per second to 1 ,5 meter per second, further preferably in the range from 0,1 meter per second to 0,3 meter per second, most preferred 0,15 meter per second.
Furthermore, if sub-step 110 is used, the brushing strokes in step 114 may for example be performed in parallel to the rolling direction of the first metal part. This may increase the connection between the metal parts.
In a further sub-step 112 of step 102, after sub-step 110, the first and second metal part may be thermally conditioned, for example, heated. The thermal conditioning may cause the formation of an intermetallic phase at the contact surfaces of the first and second metal part. Hence, the intermetallic phase may be arranged between the first metal part and the second metal part.
However, the intermetallic phase between the first and second metal part may also be formed in a different manner.
The intermetallic phase between the first and second metal part may comprise a thickness in the range from 5 pm to 40 pm, preferably in the range from 10 pm to 20 pm. If the intermetallic phase becomes too thick, the intermetallic phase may cause a decrease of the cooling performance of the multi-metal cooler.
As shown in Fig. 2a, three first metal parts 12 being strip-shaped may be rolled on a bandshaped second metal part 14. The material bond in the form of the intermetallic phase 16 attaches each first metal part 12 to the second metal part 14.
As shown in Fig. 2b, the first metal parts 12 protrude from the second metal part 14. A first outer surface 28 of the first metal part 12 faces away from the second metal part 14. The second metal part 14 further comprises a second outer surface 30 being adjacent to the first metal parts 12.
Optionally, slugs 18 may for example be punched, cut using waterjets or wire cutting / wire erosion techniques, from the combined first and second metal part as indicated in Fig. 2c. Each slug may then be formed to a multi-metal cooler in the further steps. By punching a plurality of slugs 18 from a combined first and second metal band, a high number of slugs 18 may be produced in a short time.
Fig. 3 shows a slug 18. The slug 18 is a pre-shaped multi-metal cooler, thus most dimensions of the slug 18 are close to the dimensions of the future multi-metal cooler. The slug 18 comprises three material islands formed by the first metal parts 12in the material of the second metal part 14.
In a step 104 shown in Fig. 1 , the at least one first metal part being connected to the at least one second metal part is pressed into the at least one second metal part. If the first metal part is made of copper and the second metal part is made of aluminium, the first metal part is harder than the second metal part. Pressing the first metal part into the second metal part may therefore substantially only deform the second metal part.
After pressing the first metal part into the second metal part, the first outer surface of the first metal part facing away from the second metal part and the second outer surface of second metal part adjacent to the first outer surface may be flush to each other. That means that the first outer surface and the second outer surface may be substantially arranged in a common plane.
The first outer surface and the second outer surface may be seamlessly connected to each other or comprise a thin seam in the range of 10 pm to 100 pm.
In a step 106, the second metal part is shaped into a predetermined shape of a multi-metal cooler. For example, the predetermined shape may comprise cooling fins at a side being opposite to side connected to the first metal part.
Steps 104 and 106 may be carried out simultaneously in according to step 108. Hence, while pressing the first metal part into the second metal part, shaping of the second metal part takes place. The simultaneous pressing and shaping may for example be performed by using a moulding tool, particularly a forging press. This is shown in more detail in Figs. 4a and 4b. The slug 18 is arranged on a structured mould 20 of a forging press. The first metal parts 12 face out of the structured mould. The structured mould 20 is only configured to shape the second metal part 14. The structured mould 20 comprises structures 24 for forming cooling fins.
A second mould 22 of the forging press may be arranged on the first metal parts 12 as shown in Fig. 4a. Thus, the slug 18 is sandwiched between the structured mould 20 and the second mould 22.
While closing the distance between the second mould and the structured mould, e.g. by moving the second mould 22 towards the structured mould 20, the second mould 22 presses the first metal parts 12 into the second metal part 14. The material of the second metal part 14 may flow around the first metal parts 12 until the first outer surface 28 is flush to the second outer surface 30 as shown in Fig. 4b. The material bonding between the first and second metal parts 12, 14 is pressed with the first metal part into the second metal part.
Simultaneously, the second metal part 14 is pressed into the structured mould 20 to form a multi-metal cooler 10. Cold forging may shape the second metal part 14. Due to the pressing force of the forging press, the material of the second metal part 14 flows into the structures 24 of the structured mould 20. The structures 24 of the structures mould 20 may form cooling fins 26 for the multi-metal cooler 10 on the second metal part 14.
Optionally, the forged multi-metal cooler 10 may be milled to receive a final shape of the multimetal cooler 10.
The first outer surfaces 28 may be the contact surfaces for electrical components to be cooled. The heat of the electrical components may be conducted by the first metal part via the intermetallic phase 16 to the second metal part 14. Then, the cooling fins 26 of the multi-metal cooler 10 may dissipate the heat.
Additionally or alternatively, the structured mould 20 may comprise structures for forming cooling channels (not shown) for a cooling fluid in the second metal part.
The invention is not limited to one of the aforementioned embodiments. It can be modified in many ways. All features and advantages resulting from the claims, the description and the drawing, including constructive details, spatial arrangements and procedural steps, may be essential for the invention both in themselves and in various combinations.
List of references
10 multi-metal cooler
12 first metal part 14 second metal part
16 intermetallic phase
18 slug
20 structured mould
22 second mould 24 structure
26 cooling fin
28 first outer surface
30 second outer surface

Claims

Claims
1 . A method for forming a multi-metal cooler, the method (100) comprising the following steps:
Connecting (102) at least one first metal part to at least one second metal part in a materially bonded manner;
Pressing (104) the at least one first metal into the at least one second metal part after the step of connecting the at least one first metal part to the at least one second metal part in a materially bonded manner; and
Shaping (106) the at least one second metal part into a predetermined shape of the multi-metal cooler.
2. The method according to claim 1 , wherein the steps of pressing the at least one first metal into the at least one second metal part and shaping the at least one second metal part into a predetermined shape are performed simultaneously (108), preferably by using a moulding tool, particularly a forging press.
3. The method according to claim 1 or 2, wherein the step connecting at least one first metal part to at least one second metal part in a materially bonded manner is performed by rolling (110) the at least first metal part on the at least one second metal part and/or a subsequent thermal conditioning (112) of the first and second metal part being attached to each other.
4. The method according to one of claims 1 to 3, wherein in the step connecting at least one first metal part to at least one second metal part in a materially bonded manner, an intermetallic phase between the at least one first metal part and the at least one second metal part is formed.
5. The method according to claim 4, wherein the intermetallic phase comprising a thickness in the range from 5 pm to 40 pm, preferably in the range from 10 pm to 20 pm.
6. The method according to one of claims 1 to 5, wherein the at least one first metal part is made of copper and/or the at least one second metal part is made of aluminium.
7. The method according to one of claims 1 to 6, wherein in the step of pressing the at least one first metal into the at least one second metal part, the at least one first metal part is pressed into the at least one second metal part such that an outer surface of the at least one first metal part and an outer surface of the at least one second metal part are essentially arranged in a common plane. A multi-metal cooler comprising at least one first metal part (12) and at least a second metal part (14), wherein the at least one first metal part (12) is connected to the at least one second metal part (14) in a materially bonded manner and wherein the at least one second metal part (14) defines the shape of the multi-metal cooler (10). The multi-metal cooler according to claim 8, wherein the connection between the at least one first metal part (12) and the at least one second metal part (14) comprises an intermetallic phase (16), preferably having a thickness in the range from 5 pm to 40 pm, further preferably in the range from 10 pm to 20 pm. The multi-metal cooler according to claim 8 or 9, wherein the at least one first metal part (12) is made of copper and/or the at least one second metal part (14) is made of aluminium. The multi-metal cooler according to one of claims 8 to 10, wherein a first outer surface (28) of the at least one first metal part (12) and a second outer surface (30) of the at least one second metal part (14) are essentially arranged in a common plane.
PCT/EP2023/056839 2022-03-16 2023-03-16 Multi-metal cooler and method for forming a multi-metal cooler WO2023175122A1 (en)

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CN110808232A (en) * 2019-11-19 2020-02-18 浙江天毅半导体科技有限公司 Copper-aluminum composite radiator and processing method thereof
US20220001482A1 (en) * 2018-11-28 2022-01-06 Mitsubishi Materials Corporation Bonded body, heat sink-attached insulated circuit board, and heat sink

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JPH09298259A (en) 1996-05-09 1997-11-18 Sumitomo Metal Ind Ltd Heat sink and manufacture thereof
JP6638282B2 (en) 2015-09-25 2020-01-29 三菱マテリアル株式会社 Light emitting module with cooler and method of manufacturing light emitting module with cooler

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160187080A1 (en) * 2014-12-27 2016-06-30 Ralph Remsburg Bonded aluminum-dissimilar metal structure and method of making same
US20220001482A1 (en) * 2018-11-28 2022-01-06 Mitsubishi Materials Corporation Bonded body, heat sink-attached insulated circuit board, and heat sink
CN110808232A (en) * 2019-11-19 2020-02-18 浙江天毅半导体科技有限公司 Copper-aluminum composite radiator and processing method thereof

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