JP2003046047A - Power module having electronic power component, and method of manufacturing such a module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple power module which provides superior heat dissipation of power discharged by a power component and which can be manufactured at a low cost. SOLUTION: The power module 1, having electronic power components 7, comprises a soleplate 3 constituting a heat exchanger for dumping the power dissipated due to the Joule effect in the power components. The module is provided with the soleplate 3 having a face that is provided with a skin 4 of aluminum alloy, and the skin 4 is covered in an insulating layer 5 of aluminum oxide, obtained by anodizing the skin 4. The insulating layer 5 constitutes a substrate, on which metallized tracks 6 are made, in order to receive the electronic components 7, and the other face of the soleplate 3 is in contact with a cooling fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power module having an electronic power element and a method for manufacturing such a power module. In particular, the present invention relates to a power module including a sole plate that constitutes a heat exchanger for discharging the power dissipated by the Joule effect in an electronic power device.

[0002]

2. Description of the Related Art The present invention is particularly applicable to 30 kW to 200 kW.
It is applied in the manufacture of an intermediate power range inverter for highway applications of electric vehicles, which require a power of the order of 2 and the voltage across the power module is of the order of 500V to 2000V.

Constructed from power elements brazed on an aluminum coating, arranged on one side of a ceramic substrate made of aluminum nitride AlN, the other side of the AlN ceramic substrate being covered with an aluminum coating and a heat exchanger. It is known to form a power module that is affixed to the constituent AlSiC composite sole plate. In such power modules, AlN substrates provide electrical isolation for high voltage devices to grounded AlSiC sole plates, but such AlN substrates are relatively expensive, at least 0.635 m.
Although commercially available with a minimum thickness of m, in some applications, especially for withstanding voltage in electric vehicles, a thickness of 0.1 mm is sufficient to provide insulation. Both of these drawbacks make power modules very expensive for automotive applications.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a power module which provides good heat dissipation of the power emitted by the power element and which is simple and can be manufactured at low cost. .

[0005]

SUMMARY OF THE INVENTION The present invention is a power module having an electronic power device, wherein the power module releases heat dissipated by the Joule effect within the electronic power device. And a sole plate having a surface provided with a coating made of an aluminum alloy, and the coating is covered with an insulating layer made of aluminum oxide obtained by anodizing the coating. And wherein the insulating layer constitutes a substrate on which metallized tracks are formed for housing the electronic power element, the other side of the sole plate being in contact with a cooling fluid. The power module is provided.

In particular embodiments, the power module may have one or more of the following features, individually employed or in any technically feasible combination. The sole plate is made of AlSiC composite. -The sole plate is made of aluminum. The surface of the sole plate in contact with the cooling fluid has studs or microchannels immersed in the cooling fluid, the studs or microchannels being formed directly on the sole plate or on an aluminum coating applied to the sole plate To be done. • Metallized tracks are formed by depositing copper. Electronic power devices are brazed to copper tracks. -The electronic power element is an IGBT element. -Three sets of IGBT elements are brazed on one common substrate, and the tracks of each IGBT set are separated from each other so that two substrates can form a three-phase inverter.

The present invention is also a manufacturing method for manufacturing the above power module, wherein the aluminum oxide layer is obtained by anodizing the aluminum alloy coating in sulfuric acid at about 0 ° C. And provide a method.

In various implementations, the method of manufacture may employ one or more of the following features individually, or may comprise any technically feasible combination. -The aluminum oxide layer thus obtained is immersed in warm water to form aluminum hydroxide on the surface of the aluminum oxide layer so as to reduce the porosity of the aluminum oxide layer. -The aluminum alloy coating over the sole plate is obtained directly when the sole plate is molded with an appropriately shaped mold. An aluminum oxide layer is metallized by electrolytically depositing copper on the tracks that have been pre-activated by UV laser treatment, followed by nickel plating of the copper tracks by an electroless process.

The objects, features, and advantages of the present invention will be better understood by reading the following detailed description of various embodiments, given by way of non-limiting example, and by referring to the accompanying drawings. .

To simplify the drawings, only the components necessary to understand the present invention are shown.

[0011]

1 shows a power module 1 having a portion 11 which is connected to a water manifold 10 made of molded plastic and through which cooling water flows.

The power module 1 is fixed on the water manifold 10 so as not to leak, and is made of AlSiC.
Silicon Aluminum Aluminum Carbide (AlSiC) having a bottom surface with studs 3b (shown in FIG. 2) immersed in the fluid flowing portion 11 of the manifold 10 to enhance heat exchange between the sole plate 3 and the cooling fluid. ) A sole plate 3 made of a composite material is provided. The upper surface of the AlSiC sole plate 3 has a thickness of 50 μm to 100 μm, and is between the upper and lower surfaces of the aluminum oxide layer without dielectric breakdown.
It has a coating 4 of an aluminum alloy, covered with a layer 5 of aluminum oxide, which provides electrical insulation that can withstand a potential difference of 000 V or more.

The sole plate 3 with the layer 5 of aluminum oxide is brazed to the metallized tracks 6 by three sets of insulated gate bipolar transistors (I).
The tracks 6 constitute a substrate metallized thereon in a predetermined pattern to act as a current collector for the GBT) 7. Advantageously, as shown in FIG.
The tracks 6 feeding each of the T's are separated from each other so that half of the three-phase inverter can be mounted on a single substrate.

A method of manufacturing such a power module will be described below.

The AlSiC sole plate 3 is made in a conventional manner by injecting aluminum onto the silicon carbide fibers in the mold, the shape of the mold being such that the aluminum coating 4 is formed on the upper surface of the AlSiC sole plate. Be appropriate to ensure that In a variant (not shown), the bottom surface of the sole plate 3 that comes into contact with the cooling fluid results in studs or microchannels that are formed directly during the molding process of the sole plate 3 by having an appropriately shaped mold. An aluminum coating can be provided.

The aluminum alloy coating 4 of the sole plate 3 is then covered with a layer 5 of aluminum oxide by anodizing the coating 4 in sulfuric acid. Such anodization at room temperature makes it possible to obtain aluminum oxides with a thickness of approximately 20 μm, the thickness of the aluminum oxide being limited by the dissolution of the oxide formed in sulfuric acid. The anodization is preferably 0 to obtain a thicker aluminum oxide up to 100 μm.
The oxide deposit thus obtained is immersed in warm water in order to reduce the porosity of the aluminum oxide layer 5 by forming aluminum hydroxide, which is carried out at 0 ° C.

As a matter of course, the thickness of the aluminum oxide layer 5 formed in this manner is such that when the aluminum content of the alloy is large, the thickness of the aluminum layer 5 produced by anodic oxidation becomes larger, so that the coating film 4 is formed. It depends on the aluminum content of the alloy used to do so.

The upper surface 5a of the aluminum oxide layer 5 is then covered with a track 6 which is previously activated by UV laser treatment.
Metallized by electrolytically depositing copper on it, followed by nickel plating using an "electroless" process, the deposition of the metal layer anneals at 400 ° C to 500 ° C, which is acceptable for aluminum and its alloys. Will be strengthened by A similar metallization method is described in French patent application FR-A.
1-2681078. IGBT element 7
Are then brazed on the copper tracks 6 in a conventional manner.

In this manufacturing method, the layer 5 that penetrates into the coating 4 is used.
Thereby, the heat conduction between the aluminum oxide layer 5 and the coating film 4 can be made very good. In addition, the coating 4 is A
Since it is obtained directly during the molding of the 1SiC sole plate 3, it integrates with the sole plate 3 without separating interfaces, which ensures a good thermal conductivity between the coating 4 and the sole plate 3.

This method of manufacture thus makes it possible to obtain a low-cost power module that provides good cooling of the power element, due to the very good thermal conductivity between the various layers of the power module. Furthermore, the substrate thus obtained exhibits a very small thermal expansion difference between the layers, which makes it very reliable and the risk of delamination of the brazing layer after numerous thermal cycles being very small. This manufacturing method also makes it possible to adapt the thickness of the aluminum oxide layer constituting the electrical insulation to the requirements of the power module so as to minimize the thickness of the aluminum oxide layer, thereby reducing the thermal resistance. To do.

FIG. 4 shows a second embodiment of the power module of the present invention, which differs from the first embodiment described above in that the sole plate 3 is made entirely of aluminum alloy. ing. In FIG. 4, the power module 1 comprises a sole plate 3 made of aluminum and having a bottom surface in contact with a cooling fluid, which bottom surface comprises studs 3b obtained directly during the molding of the aluminum sole plate 3. There is. The upper surface of the sole plate 3 is covered with a layer 5 of aluminum oxide obtained by anodic oxidation using a method similar to that described in the first embodiment of the invention. After that, the track is metal-coated on the aluminum oxide layer 5 by using the same method as described in the first embodiment so that the track acts as a current collector of the three sets of the IGBT elements 7, and the IGBT elements are Brazed to the track with soft tin, lead, or silver type solder that can accommodate differential expansion.

Various such embodiments of the present invention include:
Eliminating the use of 1SiC composites and replacing them with aluminum alloys helps further reduce the manufacturing cost of the power module. Nevertheless, the power module obtained in this way is unreliable when subjected to thermal cycling due to the large expansion difference between the power element and the aluminum sole plate, which makes it difficult to braze the element. Requires soft solder used for.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a power module mounted on a water manifold and constituting a first embodiment of the present invention.

FIG. 2 is a view of the power module of FIG. 1 seen from below.

FIG. 3 is a view of the power module of FIG. 1 as seen from above.

FIG. 4 is a schematic cross-sectional view of a power module that constitutes a second embodiment of the present invention.

[Explanation of symbols]

1 power module 3 sole plate 3b stud 4 film 5 insulating layers 6 tracks 7 Electronic power element 10 water manifold

Claims (12)

[Claims] 1. A power module (1) having an electronic power element (7), said power module comprising a heat exchanger for radiating the power dissipated by the Joule effect in said electronic power element. A sole plate (3) which has one surface provided with a coating (4) made of an aluminum alloy, the coating (4) anodizing the coating (4). Insulating layer (5) made of aluminum oxide obtained by
And the insulating layer (5) constitutes a substrate on which metallized tracks (6) are formed for accommodating the electronic power element (7), and the sole plate (3) The power module, wherein the other surface of the power module is in contact with the cooling fluid. 2. The sole plate (3) is made of AlSiC.
The power module according to claim 1, wherein the power module is formed of a composite material. 3. Power module according to claim 1, characterized in that the sole plate (3) is made of aluminum. 4. A stud (3b) in which the side of the sole plate (3) that contacts the cooling fluid is immersed in the cooling fluid.
Or having microchannels, characterized in that the studs (3b) or microchannels are formed directly on the sole plate (3) or on an aluminum coating applied to the sole plate (3). The power module according to any one of claims 1 to 3. 5. Power module according to claim 1, characterized in that the metallized tracks (6) are formed by depositing copper. 6. Power module according to claim 5, characterized in that the electronic power element (7) is brazed to the copper tracks (6). 7. The power module according to claim 1, wherein the electronic power element (7) is an IGBT element. 8. Three sets of IGBT elements (7) are brazed on one common substrate, and each set of tracks (6) of IGBT elements (7) is a two-phase three-phase inverter. The power module according to claim 7, wherein the power modules are separated from each other so that they can be configured. 9. A method of manufacturing a power module (1) according to claim 1, wherein the aluminum oxide layer (5) is aluminum in sulfuric acid at about 0 ° C. A manufacturing method for manufacturing a power module, which is obtained by anodizing an alloy coating (4). 10. Hot water for forming aluminum hydroxide on the surface of the aluminum oxide layer (5) so that the aluminum oxide layer (5) thus obtained reduces the porosity of the aluminum oxide layer (5). The manufacturing method according to claim 9, wherein the manufacturing method is soaked in. 11. The aluminum alloy coating (4) covering the sole plate (3) is obtained directly when the sole plate (3) is molded by means of a mold of suitable shape. Alternatively, the manufacturing method according to claim 10. 12. The aluminum oxide layer (5) is metallized by electrolytically depositing copper on the tracks (6) which have been pre-activated by UV laser treatment, the copper tracks (6) continuing. 10. An electroless process for nickel plating.
To the manufacturing method according to claim 11.