Insulated metal substrate printed circuit board with integrated cooling device

Abstract

The present invention relates to a printed circuit board (10) with an insulated metal substrate, comprising a metal support (1), at least one insulating layer (4), and at least one layer of metallic material (5) on which at least one electronic component (6) is implanted, characterized in that the metal support (1) incorporates a cooling device (3). The invention also relates to an assembly comprising the printed circuit board (10) and a base (101) arranged to form a channel (105) for the circulation of a heat transfer fluid. Figure 2

Description

Title of the invention: Printed circuit board with insulated metal substrate and integrated cooling device

[0001] The invention relates to a printed circuit board with an insulated metallic substrate, better known by the acronym IMS, meaning in English "Insulated Metallic Substrate".

[0002] The invention is of particular interest in the field of electric or hybrid vehicles, where it is essential to use on-board power electronic devices to convert an input voltage or current into a suitable output voltage or current. Such an electronic device is commonly called an on-board charger, or a DC / DC converter. The invention can also be applied to an inverter.

[0003] A printed circuit board is a substrate, generally a plate, used to electrically connect a set of electronic components together in order to create a complex electronic circuit. It is also referred to as an electronic board.

[0004] A printed circuit board with an insulated metal substrate conventionally comprises a metal substrate, typically a copper or aluminum plate, copper traces formed in a layer of copper foil and on which electronic components are mounted, and an insulating material separating the metal substrate from the copper traces. The insulating material is typically an epoxy resin. Electronic components are mounted on the copper traces at designated copper trace mounting areas. An example of a printed circuit board with an insulated metal substrate is described in document FR2969899A1.

[0005] In printed circuit boards that interconnect electronic components, there is a drawback related to the dissipation or removal of heat generated by these components. Often, the metal substrate of the insulated metal-substrate printed circuit board is not sufficient on its own to dissipate the heat necessary to prevent damage to the electronic components.

[0006] It is known to add an additional cooling device such as a heat sink or a cold plate to the insulated metal substrate printed circuit board. This additional cooling device can be thermally coupled to the copper or aluminum plate directly or indirectly via a thermal interface material.

[0007] This known arrangement has the disadvantage of being expensive, complex to assemble due to a large number of components, and having thermal dissipation capabilities limited. Furthermore, this arrangement poses problems in terms of weight and compactness. There is therefore a need to address these problems.

[0008] Thus, the invention proposes a printed circuit board with an insulated metal substrate, comprising a metal support, at least one insulating layer, and at least one layer of metallic material on which at least one electronic component is implanted. According to the invention, the metal support incorporates a cooling device.

[0009] This design makes it possible to remedy the aforementioned problems by proposing a printed circuit board with an isolated metal substrate that is compact, with good heat dissipation capabilities and simple to manufacture.

[0010] The metal support incorporating a cooling device means that the material of the metal support itself constitutes the cooling device. The metal support thus has two main functions: supporting the electronic components and actively participating in the dissipation of heat generated by these electronic components. One of the advantages of the invention is that no additional element is required to perform this function, as it is directly achieved by the geometry of the metal support.

[0011] According to the invention, the metal support is made of aluminum or copper. Aluminum is normally used as the substrate because of its low cost. Copper is used in higher power density designs because of its superior thermal conductivity. Copper also has the advantage of having a lower coefficient of thermal expansion than aluminum.

[0012] According to the invention, the cooling device comprises protrusions formed from the material of the metal support. In other words, the protrusions and the metal support are a single piece. This improves heat dissipation by conduction.

[0013] According to the invention, the protrusions are in the form of pins or fins. These shapes increase the exchange surface area between the cooling device and the external environment, in this case a heat transfer fluid.

[0014] According to the invention, the metal support has a thickness E1 and the cooling device has a thickness E2, the thickness E2 of the cooling device representing at least 50% of the thickness E1 of the metal support. This design ensures a sufficient heat exchange surface.

[0015] For example, the thickness El of the metal support is between 8mm and 9mm and the thickness E2 of the cooling device is between 5 and 6mm.

[0016] According to the invention, the electronic component is a power module. Such a power module is used in the context of an on-board charger for an electric or hybrid vehicle.

[0017] The invention also relates to an assembly consisting of a printed circuit board with an insulated metal substrate according to one of the preceding characteristics and a base forming part of a heat transfer fluid circulation channel. The printed circuit board with an insulated metal substrate is arranged on the base so as to close the heat transfer fluid circulation channel. Thus, the metal substrate of the printed circuit board and the protrusions are in direct contact with the heat transfer fluid circulating in the channel, which improves heat dissipation.

[0018] According to the invention, the base comprises a bottom wall and at least two side walls, said printed circuit board with insulated metal substrate is disposed on the at least two side walls.

[0019] Alternatively, the bottom wall can also be formed by a second printed circuit board with an insulated metal substrate having the same characteristics. With this architecture, the heat transfer fluid circulating in the channel dissipates the heat generated by two printed circuit boards with an insulated metal substrate.

[0020] According to the invention, a sealing device is disposed between the base and the printed circuit board with an insulated metal substrate. This prevents leakage of the heat transfer fluid outside the circulation channel.

[0021] Other features and advantages of the invention will become apparent from the following detailed embodiment, with reference to the attached figures:

[0022] [Fig.1] schematically represents a printed circuit according to the invention;

[0023] [Fig.2] schematically represents an assembly formed by the circuit printed from [Fig.l] associated with a base to form a heat transfer fluid circulation channel.

[0024] It should be noted that the figures disclose the invention in sufficient detail for its implementation, said figures helping to better define the invention if necessary.

[0025] With reference to [Fig.1], a printed circuit board 10 is shown with an insulated metallic substrate with the integrated cooling device 3 according to the present invention.

[0026] The printed circuit 10 is of the simplest type and includes a metallic support 1, on which is a layer of insulator 4 also called electrically insulating layer and at least one layer of metallic material 5 serving as an electro-conductive track on which is implanted at least one electronic component 6 and more precisely two electronic components 6 as seen in [Fig.1].

[0027] Preferably, the insulating layer 4 is glued to the metal support 1 and the layer of metallic material 5 is glued to the insulating layer 4. Other means of adhesion are possible as long as the materials of the different layers are compatible with these means of adhesion.

[0028] The metallic material layer 5 allows the power electronic components 6 to be connected together. This metallic layer 5 is advantageously a copper trace. The electronic components 6 are power electronic components, in particular power modules. These electronic components 6 generate significant heat due to the high currents flowing through them and must be cooled to maintain them at a temperature suitable for their operation.

[0029] The material of the insulating layer 4 is chosen in such a way that, being electrically insulating, it is the best possible thermal conductor.

[0030] Thus, a large part of the heat generated by the electronic components 6 is transferred to the metal support 1, which in this case is made of aluminum alloy.

[0031] The metal support 1 incorporates a cooling device 3 to dissipate the heat generated by the electronic component(s) 6 to an external environment. The cooling device 3 is located on a face of the printed circuit board 10 opposite the face on which the electronic components 6 are located.

[0032] To this end, the metal support 1 includes protrusions 2, preferably in the form of pins or fins, in order to increase the exchange surface area between the metal support 1 and the external environment. Other forms of protrusions are possible provided they can be easily manufactured in the context of a metal support used in a printed circuit board 10 with an insulated metal substrate.

[0033] The protrusions 2 are obtained by extrusion, machining, or molding of the metal support 1. The protrusions 2 are arranged in a matrix pattern on the metal support 1 to form a succession of rows and columns. The protrusions 2 extend in a direction perpendicular to the direction of extension of the metal support 1.

[0034] The metal support 1 has a thickness El and the cooling device has a thickness E2, the thickness E2 of the cooling device represents at least 50% of the thickness El of the metal support.

[0035] Fig. 2 shows an assembly 100 formed by a printed circuit 10 as described above and a base 101 forming part of a channel 105 for circulating heat transfer fluid, for example glycol water.

[0036] The printed circuit board 10 is arranged on the base 101 so as to close the heat transfer fluid circulation channel 105. Thus, the metal support 1 and the protrusions 2 are in direct contact with the heat transfer fluid.

[0037] The base 101 comprises a bottom wall 102 and at least two side walls 103; the printed circuit board 10 with an insulated metal substrate is disposed indirectly or directly on the at least two side walls 103. A sealing device 104, for example in the form of an O-ring, is placed between the base 101 and the printed circuit board 10.

[0038] In an alternative embodiment not shown, the printed circuit board may include a metallic support 1 on one side of which several alternating layers of insulator 4 and metallic material 5 serve as an electro-conductive track.

[0039] Although the invention has been described in connection with a particular embodiment, it is clearly evident that it is by no means limited to it and that it includes all technical equivalents of the means described.

[0040] In the claims, the reference symbols in parentheses shall not be interpreted as a limitation of the claim.

Claims

Demands

1. Printed circuit board (10) with insulated metal substrate, comprising a metal support (1), at least one layer of insulation (4) and at least one layer of metallic material (5) on which is implanted at least one electronic component (6) characterized in that the metal support (1) incorporates a cooling device (3).

2. Printed circuit board according to claim 1, characterized in that the metal support (1) is made of aluminium or copper.

3. Printed circuit board (10) according to any one of the preceding claims, characterized in that the cooling device (3) comprises protrusions (2) originating from the material of the metallic support (1).

4. Printed circuit board (10) according to any one of the preceding claims, characterized in that the protrusions (2) are made in the form of pins or fins.

5. Printed circuit board (10) according to any one of the preceding claims, characterized in that the metal support (1) has a thickness El and the cooling device (3) has a thickness E2, the thickness E2 of the cooling device (3) represents at least 50% of the thickness El of the metal support (1).

6. Printed circuit board (10) according to any one of the preceding claims, characterized in that the electronic component (6) is a power module.

7. Assembly (100) formed by a printed circuit board (10) with an insulated metal substrate according to any one of the preceding claims and a base (101) forming part of a heat transfer fluid circulation channel (105), said printed circuit board (10) with an insulated metal substrate is arranged on the base (101) so as to close the heat transfer fluid circulation channel (105).

8. Assembly according to the preceding claim, characterized in that the base (101) comprises a bottom wall (102) and two side walls (103), said printed circuit board (10) with insulated metal substrate is disposed on the two side walls (103).

9. Assembly (100) according to the preceding claim, characterized in that a sealing device (103) is disposed between the base (101) and the printed circuit board (10) with insulated metal substrate.

10. 7 Assembly (100) according to claim 8, characterized in that the bottom wall (102) is formed by a second printed circuit (10) with an insulated metal substrate according to any one of claims 1 to 6.

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