WO2006069855A1 - Arrangement of an electrical component and a two-phase cooling device - Google Patents

Abstract

The invention relates to an arrangement (1) of at least one electrical component (2) and at least one cooling device for the extraction of heat arising during operation of said component. The arrangement is characterised in that the cooling device is at least a two-phase cooling device (3), comprising at least one evaporator (31), for a cooling fluid (34) and an electrical insulation film (4), arranged between the component and the evaporator. The two-phase cooling device is embodied as a thermosiphon, heatpipe, or heatplanar. An efficient cooling of electrical components, in particular, of power semiconductor components (21) in a power semiconductor module (26) with simultaneous effective electrical insulation of the evaporator of the two-phase cooling device and the component itself are possible. A high integration density is also possible.

Description

description

Arrangement of an electrical component and a two-phase cooling device

The invention relates to an arrangement of at least one electrical component and at least one cooling device for dissipating heat that arises during operation of the component.

Such an arrangement is, for example, a power semiconductor module known from WO 03/030247 A2. The electrical component of the power semiconductor module is a power semiconductor component which is arranged on a substrate (circuit carrier). The substrate is, for example, a DCB (Direct Copper Bonding) substrate, which consists of a carrier layer of a ceramic material, on both sides of which electrically conductive layers of copper (copper foils) are applied. The ceramic material is, for example, aluminum oxide (Al ₂ O ₃ ). The

Power semiconductor device is soldered on one of the electrically conductive layers of copper.

During operation of the power semiconductor component, a certain amount of heat is generated. This amount of heat is dissipated by heat conduction away from the power semiconductor device. The heat conduction takes place via the solder layer between the power semiconductor component and the electrically conductive copper layer towards the carrier layer of the substrate made of aluminum oxide. The specific one

Thermal conductivity coefficient λ of aluminum oxide is about 30 Wm ^ -K ^"1. Therefore, the carrier layer of the substrate or the entire substrate functions as a cooling device for dissipating the amount of heat generated during operation of the power semiconductor device. During operation of the power semiconductor component, such a strong evolution of heat may occur that the cooling effect of the substrate is insufficient. As a result, the power semiconductor device or the device of the power semiconductor device on the substrate may be damaged.

From B. Palm, Transactions of the ASME, Vol. 125 (2003) pp. 276-281, a two-phase cooling device for cooling an electrical component emerges. The two-phase cooling device consists essentially of an evaporator (evaporator) for evaporating a cooling fluid, a condenser (condenser) for liquefying the cooling fluid and a fluid channel for transporting the cooling fluid as both liquid and gaseous phase.

The two-phase cooling device allows using the evaporation and condensation heat of the cooling fluid (coolant) a high heat flux density. The high heat flow density results as follows: The evaporator is thermally conductively connected to the electrical component. The heat generated during operation of the electrical component is transferred to the evaporator. The transferred heat leads to the evaporation of the liquid cooling fluid. The cooling fluid passes from the liquid phase to the gaseous phase. The cooling fluid absorbs heat of vaporization. Through the fluid channel, the gaseous cooling fluid passes to the condenser. The condenser is thermally conductively connected to a heat sink. In the condenser, condensation of the gaseous cooling fluid occurs. The cooling fluid passes from the gaseous phase into the liquid phase. This heat of condensation is released to the heat sink. With the participation of the two phase transitions of the cooling fluid, a high heat flux density and thus an efficient heat transfer from the component away to the heat sink result. Through the fluid channel, the liquefied at the condenser cooling fluid is transported back to the evaporator. Thus, there is a closed material cycle. Depending on the configuration of the fluid channel and the type of return transport, a distinction is made between two types of two-phase cooling devices: In a so-called "thermosiphon", the return transport takes place essentially on account of gravity, in contrast with a so-called "heat pipe". the return transport essentially due to capillary forces instead.

In order to achieve a good thermal connection to the electrical component or to the heat sink, both the evaporator and the condenser have a highly thermally conductive metal, such as aluminum or

Copper. These materials are not only thermally but also highly electrically conductive.

The object of the present invention is to show how an electrical component can be cooled efficiently.

To achieve the object, an arrangement of at least one electrical component and at least one cooling device for dissipating heat is specified, which arises during operation of the component. The arrangement is characterized in that the cooling device has at least one two-phase cooling device with at least one evaporator of a cooling fluid and between the component and the evaporator of the two-phase cooling device, an electrical insulation film is arranged.

By this arrangement, heat generated during operation of the device can be efficiently dissipated. At the same time provided for electrical insulation, so that there is no short circuit between the device and the evaporator. The insulating film may be directly or indirectly connected to the device and the evaporator. For example, the insulating film is glued directly onto the component or to an electrical connection line for electrical contacting of the component. Preferably, the insulating film is laminated to the device or to the electrical connection line for making electrical contact with the device. The lamination preferably takes place without adhesive. The insulation film is not glued on. By the method for large-area contacting described above, a large-scale connection line can be generated. By lamination of the insulating film on such a connecting line, a high heat flux density can be achieved.

Preferably, the insulation film is laminated onto the component in such a way that a surface contour of the component is imaged in a surface contour of the insulation film which faces away from the component. A topography of the component is molded. For this purpose, the lamination is preferably carried out under application of a vacuum, wherein a particularly intimate and firm contact between the component and the insulating film or the electrical connection line and the insulating film is formed. Due to the intimate and firm contact a particularly good thermal connection and at the same time a robust construction are achieved.

As an electrical insulation material of the insulation film any plastic is conceivable. The insulating film preferably has an electrical insulation material selected from the group consisting of liquid-crystalline polymer, organically modified ceramic, polyacrylate, polyimide, polyisocyanate, polyethylene, polyphenol, polyether ether ketone, polytetrafluoroethylene and / or epoxide. A necessary film thickness (film thickness) of the insulating film used depends on various factors, for example on the insulating material of the insulating film, on a heat flow to be achieved by the insulating film or also on the conditions under which the arrangement is operated.

These specified insulation materials are usually characterized by relatively low thermal conductivity coefficients. In order nevertheless to achieve a necessary for the efficient cooling of the device thermal conductivity, a relatively thin insulating film is used. The film thickness of the insulation film is so high that still sufficient electrical insulation is ensured. For example, the film thickness is selected, for example, from the range of 10 microns to 50 microns.

In order to achieve a high thermal conductivity combined with a high electrical insulation effect, the insulating film has, in a special embodiment, thermally conductive material. The insulation film consists of a composite material with the electrical insulation material as the base material and with the thermally conductive material as a filler. The thermally conductive material is preferably electrically insulating. Particularly suitable are ceramic materials such as aluminum oxide or aluminum nitride. These materials are added to the base material of the insulating film as a powder.

The evaporator and the electrical component are thermally conductively connected to one another via the insulating film. For this purpose, the evaporator of the two-phase cooling device is glued to the electrical insulation film in a particular embodiment. The evaporator and the

Insulation foil are connected to each other via an adhesive layer connected. For a good thermal connection, the adhesive preferably has thermally conductive particles.

In a further embodiment, the evaporator of the two-phase cooling device and the electrical insulation film are connected to one another via a pressure contact. The evaporator and the insulation film are pressed against each other. This is achieved, for example, with a pretensioning device. For a good thermal connection is also ensured here for the largest possible connection area.

The cooling device is suitable for cooling a single component. Due to the efficient heat transport, the cooling device is particularly suitable for the simultaneous cooling of a plurality of electrical components, which are arranged in a relatively small space to each other. Therefore, in a particular embodiment, the arrangement has a carrier body with a number of electrical components. The carrier body is for example a substrate. On the substrate several components to be cooled can be arranged relatively close to each other. This results in an increased compared to the prior art integration density (number of electrical components per unit area or volume of the carrier body). In addition, electrical connection lines between the components can be made very short, with the result that lower electrical losses occur in the connecting lines.

In a particular embodiment, at least one heat spreader is arranged between the electrical insulation film and the component in order to reduce a lateral (flat, ie not in the thickness direction of the insulation film) thermal gradient in the insulation film caused by the operation of the component. As a result, temperature peaks are avoided during operation of the device, which could lead to damage to the insulation film or the entire assembly. Through the use of Heat spreaders can be additionally increased integration density.

To improve the cooling performance, it is advantageous to use a plurality of two-phase cooling devices or a plurality of evaporators and condenser. To save space, according to a particular embodiment, the two-phase cooling device on at least two evaporators, which are connected to a condenser of the cooling fluid via at least one fluid channel for transporting the cooling fluid. Preferably, a plurality of fluid channels are present.

The two-phase cooling device is preferably selected from the group thermosiphon and / or heat pipe and / or heat planar. "Heatplanar" is a surface design of the "Heatpipe".

The electrical component may be any active or passive electrical component in which it must be dissipated during operation to such a heat development that heat. According to a particular embodiment, the component is a semiconductor component. The semiconductor component is, for example, an SMD (Surface Mounted Device) component applied to a circuit carrier. In a particular embodiment, the semiconductor component is a power semiconductor component. The

Power semiconductor component is preferably selected from the group diode, MOSFET, IGBT, thyristor and / or bipolar transistor.

In summary, the following particular advantages result with the present invention:

Due to the insulation film is a very good thermal connection of the evaporator of the two-phase cooling device to the device at the same time very good electrical Insulation of the evaporator and the component guaranteed each other.

This results in efficient cooling of an electrical component, in particular one

Power semiconductor device or a whole power semiconductor module.

The cooling is so efficient that a compact, space-saving construction results. On a relatively large, voluminous heat sink can be omitted.

It can be achieved in comparison with the prior art increased integration density. This applies in particular to a power semiconductor module having a plurality of power semiconductor components.

To produce the arrangement, known methods for large-area, electrical contacting of components and in particular of

Power semiconductor devices are used.

With reference to several embodiments and the associated figures, the invention will be described in more detail below. The figures are schematic and do not represent true to scale figures.

FIG. 1 shows an arrangement in a lateral cross-section.

Figure 2 shows a section of the Anorndung in a lateral cross-section.

The exemplary embodiments relate in each case to an arrangement 1 of at least one electrical component 2 and at least one cooling device for dissipating heat which arises during operation of the component 2. The cooling device is a two-phase cooling device 3 with an evaporator 31 for a Cooling fluid 34 and a condenser 32 for condensing the cooling fluid 34. The evaporator 31 and the condenser 32 have thermally highly conductive aluminum.

Between the electrical component 2 and the evaporator 31 of the two-phase cooling device, an electrical insulation film 4 is arranged. The insulating film 4 is configured and applied in such a way that the electrical component 2 and the evaporator 31 are electrically insulated from one another and at the same time an efficient heat conduction path from the component 2 to the evaporator 31 is present. For this purpose, the insulating film 4 on thermally conductive particles. These particles have alumina.

The evaporator 31 is connected via a fluid passage 33 with the

Condenser 32 connected. The gaseous cooling fluid 34 passes through the fluid channel 33 to the condenser 32 or the liquid cooling fluid 34 from the condenser 32 to the evaporator 31. For this purpose, the two-phase cooling device is designed as a "heat pipe." Alternatively, the two-phase cooling device is a thermosyphon ,

The condenser 32 is in thermal contact with a heat sink 35. The heat sink 35 has a copper block with cooling fins. In addition, the heat sink has a heat sink fluid which is conducted past the copper block to absorb heat. According to a first embodiment, the heat sink fluid is air which is guided past the cooling fins of the heat sink 35 by means of a fan (not shown). According to another embodiment, the heat sink fluid is a liquid. The liquid is water, which has a high heat capacity and is therefore particularly suitable for absorbing heat. The water is passed by means of a pump, not shown, on the heat sink. The electrical component 2 is a

Power semiconductor device 21 in the form of a MOSFET. In an alternative embodiment, the power semiconductor device 21 is an IGBT.

The power semiconductor component 21 is part of a power semiconductor module 26. In the power semiconductor module 26, a plurality of power semiconductor components 21 are applied to a substrate 5. The substrate 5 is a DCB substrate. The DCB substrate has a carrier layer 51 of aluminum oxide and electric power layers 52 and 53 of copper applied to both sides (FIG. 2).

On a surface portion 55 of the DCB substrate 5, which is given by the conductor layer 52, is an electrical component 2 in the form of a

Power semiconductor device 21 soldered. The solder layer 24 results. The power semiconductor component 21 is soldered such that a contact surface 22 of the lead semiconductor component 21 pointing away from the DCB substrate 5 results. For large-area, planar electrical contacting of the contact surface 22 of the power semiconductor component 21, a further insulating film 6 is laminated under vacuum. The others

Insulation film 6 is laminated onto the DCB substrate and the power semiconductor components 21 in such a way that a surface contour 23 of the power semiconductor component 21 and a surface contour 54 of the DCB substrate 5 are imaged in a surface contour 61 of the further insulation film 6 that corresponds to the DCB substrate 5 and the power semiconductor component 21 is turned away. The topography, which results from the power semiconductor component 21 and the substrate 5, is formed by the further insulation film 6. Through a window 62 of the further insulating film 6, the contact or the contact surface 22 of the

Power semiconductor device 21 electrically contacted. For this purpose, the window 62 is generated in the further insulating film 6 by laser ablation. The planar electrical contacting of the contact surface 22 of the power semiconductor device 21 is generated by a multi-layer deposition 25 of electrically conductive materials.

The power semiconductor module 26 is soldered onto the copper block of the heat sink 35 via the further electrical conduction layer 53. There is another layer of solder 56. Via the solder layer 24, the electrical conduction layer 52, the aluminum oxide layer 51, the further conduction layer 53 and the further solder layer 56, there is thus a further heat conduction path from the power semiconductor component 21 to the heat sink 35.

The insulation film 4, which is between the

Power semiconductor device 21 and the evaporator 31 is laminated (see, further insulating film 6). According to Figure 2, the insulating film 4 is laminated to the deposit 25, which is the connecting line for making electrical contact with the contact surface 22 of the

Power semiconductor device 21 forms. Thus, the surface contour of the deposition is imaged in a surface contour of the insulating film. It is the topography of the deposition 25 and the connecting line molded. In this form, the deposition 25, which serves primarily for electrical contacting, is a component of the heat conduction path from the power semiconductor component 21 to the evaporator 31. The insulation film 4 ensures that no short circuit occurs between the evaporator 31 and the deposition 25. Alternatively or in combination with the embodiment described above, the insulation film 4 is laminated directly onto the power semiconductor component 21 in such a way that the surface contour of the power semiconductor component 21 is imaged in the surface contour of the insulation film 4, which has turned away from the power semiconductor component 21. The topography of the power semiconductor device 21 is formed by the insulating film 4.

The evaporator 31 and the power semiconductor component 21 are connected to one another in a thermally conductive manner. For this purpose, according to a first embodiment, the evaporator 31 is adhesively bonded to the insulating film 4 on the upper side of the power semiconductor module 26 with the aid of a thermally conductive adhesive. There is a thermally conductive adhesive layer 41. Via the adhesive layer 41, efficient heat transport takes place from the power semiconductor component 21 to the evaporator 31 of the two-phase cooling device.

In an alternative embodiment, the evaporator 31 and the insulating film 4 by a pressure contact with each other. The evaporator 31 and the insulating film 4 are not glued together, but are pressed against each other.

Further exemplary embodiments result from the fact that a plurality of evaporators 31, a plurality of condensers 32 and / or a plurality of heat sinks 35 are used. In further embodiments, heat spreaders (not shown) are used. The heat spreaders ensure the lowest possible lateral heat or temperature gradient in the insulation film 4. This avoids temperature peaks that could lead to damage to the insulation film 4 or the entire arrangement. Through the use of heat spreaders, the integration density is additionally increased compared to the prior art.

Claims

claims 1. arrangement (1) of at least one electrical component (2, 21) and at least one cooling device for dissipating heat generated during operation of the component (2, 21), characterized in that the cooling device comprises at least one two-phase cooling device (3) with at least one evaporator (31) of a Cooling fluid (34) and between the component (2, 21) and the evaporator (31) of the two-phase cooling device, an electrical insulation film (4) is arranged. 2. Arrangement according to claim 1, wherein the insulating film (4) on the component (2, 21) is laminated. 3. Arrangement according to claim 2, wherein the insulating film (4) is laminated onto the component (2,21) such that a surface contour (23) of the component (2, 21) is imaged in a surface contour of the insulating film (4) the component (2, 21) is turned away. 4. Arrangement according to one of claims 1 to 3, wherein the insulating film (4) comprises one of the group of liquid-crystalline polymer, organically modified ceramic, polyacrylate, polyimide, polyisocyanate, polyethylene, polyphenol, polyetheretherketone, polytetrafluoroethylene and / or epoxy selected electrical insulation material. 5. Arrangement according to one of claims 1 to 4, wherein the electrical insulation film (4) comprises thermally conductive material. 6. Arrangement according to one of claims 1 to 5, wherein the Evaporator (31) of the two-phase cooling device (3) is glued to the electrical insulation film (4). 7. Arrangement according to one of claims 1 to 6, wherein the Evaporator (31) of the two-phase cooling device (3) and the electrical insulation film (4) are connected to each other via a pressure contact. 8. Arrangement according to one of claims 1 to 7, comprising a carrier body (5) with a number of electrical components (2, 21). 9. Arrangement according to one of claims 1 to 8, wherein between the electrical insulation film (4) and the Component (2, 21) a heat spreader is arranged to reduce a caused by the operation of the device lateral thermal gradient in the insulating film (4). 10. Arrangement according to one of claims 1 to 9, wherein the two-phase cooling device (3) has at least two evaporators (31) connected to a condenser (32) of the cooling fluid (34) via at least one fluid channel (33) for transporting the cooling fluid (34) are connected. 11. Arrangement according to one of claims 1 to 10, wherein the two-phase cooling device (3) from the group thermosiphon and / or heat pipe and / or heat planar is selected. 12. Arrangement according to one of claims 1 to 11, wherein the device is a semiconductor device. 13. Arrangement according to claim 12, wherein the semiconductor component is one of the group IGBT, diode, MOSFET, thyristor and / or bipolar transistor is selected power semiconductor device.