Cooling device

Abstract

A cooling device (105) for an electrical assembly (110) having a carrier (125) to which a component (130) to be cooled is attached, the cooling device (105) comprising the following elements: a heat pipe (115) having a first end configured to absorb heat; a holding element (120) for attaching the heat pipe (115) to the carrier (125) such that the first end of the heat pipe (115) is thermally coupled to the component (130); wherein the heat pipe (115) is adapted to be deformed in the region of the first end in order to compensate for a deviation of a position of the component (130) from a predetermined position (135) with respect to the carrier (125); further comprising a heat sink (205) for engagement between the component (130) and the first end of the heat pipe (115); wherein the heat sink (205) can be attached to the holding element (120) by means of a spacer, wherein a size of the spacer determines a position of the heat sink (205) relative to the holding element (120).

Description

The present invention relates to a cooling device. In particular, the invention relates to a cooling device for an electrical assembly.An electrical assembly comprises a component which is to be actively cooled. The component is arranged on a carrier, which can be formed / illustrated by a printed circuit board, for example, and the cooling device is to be attached to the carrier. The cooling device is intended to load the structural element as little mechanically as possible, and at the same time good thermal connection of the cooling device to the structural element is intended to be ensured.The position of the component may be subject to a predetermined tolerance, which may be caused, for example, by a soldering process with which the component is attached to the carrier. A distance between an abutment surface of the component and an abutment surface of the cooling device can therefore vary. If the distance is greater than intended, a thermal resistance between the elements can be increased, so that there is the risk of the component overheating. If it is smaller than intended, a mechanical stress may be applied to the component, which may lead to a defect of the assembly, for example if an electrical connection of the component is over-strained.It has been proposed to place a type of cooling body between the cooling device and the component, wherein dimensions of the cooling body are selected depending on an actual position of an individual component with respect to the carrier. However, the production and storage of a sufficient pallet of heat sinks of different thicknesses can be complicated.DE 20 2010 014 106 U1 discloses a heat distributor with a flexibly mounted heat pipe. DE 10 2011 052 710 A1 shows a heat pipe fastening method and a heat pipe assembly. EP 3 422 403 A1 shows a cooling device.It is an object of the present invention to provide an improved cooling device for cooling a component of an electrical assembly. The invention achieves this object by means of the subject matter of the independent claims. Dependent claims represent preferred embodiments.A cooling device for an electrical assembly having a carrier to which a component to be cooled is attached includes a heat pipe having a first end configured to receive heat; and a support member for attaching the heat pipe to the carrier such that the first end of the heat pipe is thermally coupled to the component. In this case, the heat pipe is configured to be deformed in the region of the first end in order to compensate for a deviation of a position of the component from a predetermined position with respect to the carrier.It has been recognized that an adaptation of the cooling device to an actual position of an individual component on an assembly can be made easier by deforming the cooling device itself. This can be achieved well in particular if the cooling device comprises a heat pipe (also called a heat pipe). The heat pipe typically comprises a hermetically sealed pipe having first and second ends, wherein a fluid is received in the heat pipe. The heat pipe is configured to direct vaporising fluid in gaseous state at the first end to the second end and direct condensed fluid in liquid state at the second end to the first end. A capillary effect can be utilized for conducting the liquid fluid, for example by arranging a wick or a similar, finely structured element in the tube. The heat pipe can also be designed as a water-conducting pipe.The tube can easily be deformed sufficiently to compensate for variance in the position of the structural member. Since the heat pipe is hollow and usually no incompressible body is accommodated in the region of the first end, the deformation can take place by means of relatively low forces and can be easily and precisely controlled. The heat pipe can thus be individually adapted for attachment to a predetermined electrical assembly. The adaptation can be effected in a meaningful manner within the scope of series production of cooling devices for electrical assemblies.The deforming preferably comprises a compressing. It is preferred that the heat pipe is compressible to a predetermined amount in the region of the first end. The compression is usually carried out in such a way that a distance between the heat pipe and the component is brought to a predetermined extent. The predetermined measure may include a predetermined range. The deformation can also be effected in such a way that tilting of the component with respect to the predetermined position is compensated.The heat pipe can be produced with an excess size first, so that in any case it must be deformed at the first end in order to be inserted on the assembly, even if the component deviates only minimally or not at all from its predetermined position or if its position assumes an extreme value in a predetermined range.It is further preferred that at least a part of the deformation is plastic. The deformation of the first end is achieved, for example, by means of a upsetting or pressing tool by introducing a predetermined deformation force or deformation path. A plastic portion of the deformation is retained after the application of force has ended, while an elastic portion of the deformation is dissipated again in the manner of a spring. The plastic deformation can ensure that no elastic force is exerted on the structural element by the cooling device. A mechanical stress on the component by the cooling device can be low. The plastic deformation can be achieved by making the heat pipe from a readily deformable and preferably highly thermally conductive material such as copper or aluminum. An element received within the heat pipe may be sized or configured so as not to impede the deformation of the pipe and not to itself limit its function.If the cooling device is attached to the carrier, it is preferred that the heat pipe is arranged between the holding element and the structural element. The holding element usually has predetermined dimensions and is preferably configured to bear at a predetermined position on the carrier of the assembly.A position of the holding element with respect to the assembly is therefore independent of the position deviation of the structural element. The deformation of the heat pipe can thus be dimensioned as a function of the determined position deviation of the component in order to enable a secure and as extensive as possible contact of the first end of the heat pipe on the component. A heat transfer between the structural element and the cooling device can thereby be improved.In a further preferred embodiment, a cross section of the undeformed heat pipe in the region of the first end is round, oval or ellipsoidal. In particular, it is preferred that the cross section is curved in a circumferential manner, i.e. preferably has neither a bend nor a planar section. A deformability of the heat pipe can thereby be increased. In addition, it is possible to prevent mechanical stresses from building up, for example in the region of a corner or a bend, which could lead to material fatigue after prolonged operation of the cooling device and, as a result, to leakage of the heat pipe.The component can have an abutment surface with a predetermined contour, wherein the heat pipe is configured to be deformed in the region of the first end in such a way that it abuts the abutment surface of the component. In particular, a planar contact of the heat pipe on the structural element can be effected. In one embodiment, the contour is planar and the heat pipe is configured to be flattened in the region of the first end. In another embodiment, the contact surface is shaped differently, for example in the form of a groove, wherein the heat pipe is configured to be deformed into a shape corresponding to the contact surface. Usually, the heat pipe already has the approximate shape of the contact surface before the deformation.In one embodiment according to the invention, the cooling device comprises a cooling body for bearing between the component and the first end of the heat pipe. The heat sink can be configured to bear against differently shaped contact surfaces of the component and of the heat pipe. For example, a first side of the heat sink can be flat in order to abut against a flat contact surface of the component and an opposite second surface can be groove-shaped in order to abut against the tube- or rod-shaped first end of the heat pipe. Other shapes are also possible.A first system includes a cooling device described herein and an electrical assembly having a carrier and a component attached to the carrier. The system may form a separately manipulable unit which can be easily installed at its destination. The system can be configured in particular for application on board a vehicle, further preferably a motor vehicle. Environmental conditions typical of a vehicle, in particular vibrations, strong accelerations or variable environmental temperatures, can be better resisted by the attachment of the heat pipe to the component to be cooled according to the invention.Another system includes a cooling device with a heat sink described herein. According to the invention, the heat sink can be attached to the holding element by means of a spacer, and wherein a size of the spacer determines a position of the heat sink with respect to the holding element. Furthermore, the system comprises a plurality of spacers of different sizes for positioning the cooling body. By selecting a suitably large spacer, the cooling body can be positioned on the holding element in such a way that it bears well against the electrical component when the cooling device is attached to the carrier of the assembly. In this embodiment as well, both a height deviation in the position of the component and a tilting can be compensated. The system can be used to provide a cooling device to an assembly, which cooling device is individually adapted to the assembly in such a way that an efficient and mechanically low-stress cooling can take place after the cooling device has been mounted on the assembly.A first method of manufacturing a system comprising a cooling device and an electrical assembly having a carrier and a component attached thereto, wherein the cooling device comprises a heat pipe having a first end configured to receive heat, comprises steps of determining a deviation of a position of the component from a predetermined position with respect to the carrier; deforming the heat pipe in the region of the first end depending on the determined deviation; and attaching the heat pipe in a predetermined position with respect to the carrier such that the first end of the heat pipe is thermally coupled to the component.In a first variant, the deformation of the heat pipe can take place before the mounting of the cooling device on the assembly. For this purpose, the heat pipe can be suitably deformed, for example, by means of a hydraulic or mechanical press. In a second variant, the deforming of the heat pipe can take place as part of the attachment of the cooling device to the assembly. The deformation of the heat pipe is preferably at least partially plastic, so that the heat pipe can abut the structural element particularly accurately without causing excessive mechanical stresses.Another method of manufacturing a system comprising a cooling device and an electrical assembly having a carrier and a component mounted to the carrier, the cooling device comprising a support member and a heat pipe having a first end configured to receive heat, comprising steps of determining a deviation of a position of the component from a predetermined position relative to the carrier; selecting a spacer whose size corresponds to the determined deviation; placing the spacer between a heat sink and the support member; deforming the first end of the heat pipe until the spacer abuts between the heat sink and the support member; and mounting the support member to the carrier such that the first end of the heat pipe is thermally coupled to the component.Here too, in a first variant, the deforming of the heat pipe can take place before the mounting of the cooling device on the assembly, or in a second variant within the scope of the mounting.The processing device can be configured to execute a method described herein in whole or in part. For this purpose, the processing device can comprise a programmable microcomputer or microcontroller and the method can be in the form of a computer program product having program code means. The computer program product can also be stored on a computer-readable data carrier. Features or advantages of the method can be transferred to the device or vice versa.The invention will now be described in more detail with reference to the accompanying figures, in which: FIG. 1 shows a system with a cooling device; FIG. 2 shows a further embodiment of a system with a cooling device; and FIG. 3 shows a flow diagram of a methodis.FIG. 1 shows a system 100 comprising a cooling device 105 and an electrical assembly 110. In an upper region, the system 100 is shown in a first production phase, and in a second production phase in the lower region. The system 100 is preferably configured to be used on board a vehicle, in particular a motor vehicle. The system 100 should be as resistant as possible to influences such as vibrations, high or low temperatures, a change in position, an acceleration or a mechanical, electrical or thermal continuous load.The cooling device 105 includes at least one heat pipe 115 and a holding member 120. A heat pipe 115 typically includes two spaced apart ends, only a first end of which is visible in FIG. 1. In the embodiment shown in FIG. 1, a plurality of first ends of a plurality of heat pipes 115 are visible; for the sake of clarity, only one heat pipe 115 is used below.A fluid and a capillary element are usually located in the heat pipe 115. The capillary element can be constructed in the manner of a wick and can be formed / illustrated, for example, by a braid of wire, in particular copper wire. In the case of a gravity-driven heat pipe 115, the capillary element can also be dispensed with. The fluid can evaporate in the region of the first end, wherein it absorbs thermal energy. The gaseous fluid may then be directed from the first end to the second end where it may condense to give off heat. In the region of the second end, for example, a radiator, an air cooling body or an active liquid cooling can be provided. The liquid fluid may be returned from the second end to the first end, which may alternatively be effected by means of the capillary element or by gravity. The fluid and an operating pressure of the fluid in the heat pipe 115 may be selected depending on cooling requirements. Exemplary fluids include water, ammonia, or methane.The electrical assembly 110 comprises a carrier 125 to which a component 130 is attached. The carrier 125 can comprise in particular a printed circuit board (also: PCB, or board) and is usually planar. The component 130 can comprise, in particular, an electrical or electronic power component which can be configured, for example, to be flowed through by a significant electrical current. The component 130 can comprise, for example, a processing device, in particular a CPU or GPU, or a power semiconductor such as a bipolar or a field effect transistor. The component 130 can be attached to the carrier 125 by means of soldering. In particular, if solder joints are located between the component 130 and the carrier 125, for example if the component 130 is arranged in a BGA package, a position of the component 130 may deviate from a predetermined position 135. The deviation can be determined in the vertical direction, i.e. perpendicular to the carrier 125. The deviation may also relate to a tilting of the component 130 if the component 130 assumes an angle other than a predetermined angle with respect to the carrier 125. It can usually be assumed that the deviation from the predetermined position 135 does not exceed a predetermined amount. This dimension can be, for example, approximately ±0.2 mm.It is proposed to deform the heat pipe 115 in the region of its first end as a function of an actual position of the component 130 with respect to the carrier 125 in such a way that it bears as well as possible against the component 130 when the cooling device 105 is attached to the assembly 110.In the upper portion of FIG. 1, the cooling device 105 and the assembly 110 are separated from each other, and the first end of the heat pipe 115 is in an undeformed state. Purely by way of example, a circular cross section of the undeformed first end of the heat pipe 115 is assumed here. By means of a tool 140, the first end of the heat pipe 115 can be deformed in a predetermined manner. The tool 140 can comprise, for example, a punch which can be actuated, in particular hydraulically. The actuation includes a predetermined movement of the tool 140, wherein the first end of the heat pipe 115 is pressed against an abutment so as to be deformed between the tool 140 and the abutment. In the present embodiment, the abutment is formed by the holding element 120, which preferably has a depression in which a section of the first end of the heat pipe 115 can preferably bear flat.In the embodiment shown, an upper contact surface of the component 130 is planar and the tool 140 likewise comprises a planar contact surface for the heat pipe 115 in order to deform the latter in such a way that it receives a contact surface corresponding to the contact surface of the component 130.In the lower view of FIG. 1, the heat pipe 115 is deformed in an intended manner, and the cooling device 105 is attached to the assembly 110. The holding element 120 can completely cover the cooling device 105 in the manner of a cover or housing on a side facing away from the carrier 125.On an opposite side with respect to the carrier 125, a further cover 145 may be provided to protect the electrical assembly 110.The holding element 120 is preferably configured to be attached to the carrier 125 of the assembly 110 in a predetermined position. For this purpose, the holding element 120 and the carrier 125 can have mutually corresponding contact surfaces. It is intended that the heat pipe 115 in the region of its first end is intentionally deformed such that it forms a contact surface for the structural element 130, which, after the mounting of the retaining element 120 on the assembly 110, bears as accurately as possible against the corresponding contact surface of the structural element 130. A heat transfer can be improved by an intermediate heat conducting element 150, which can be applied in liquid or paste form. A fixed heat conducting element 150 which flows under higher thermal load in order to conform to the adjoining surfaces is also possible.FIG. 2 shows a further embodiment of a system 100 with a cooling device 105 and an electrical assembly 110. In the upper region of FIG. 2, only the cooling device 105 is shown before deforming the heat pipe 115; in the lower region, the cooling device 105 is shown attached to the electrical assembly 110 with the retaining element 120 deformed. In contrast to the embodiment shown in FIG. 1, a heat sink 205 is provided, which may be situated between the end of the heat pipe 115 and the component 130. A heat conducting element 150 can be used on one or two sides.The heat sink 205 is preferably shaped in such a way that it bears on the electrical component 130 on one side as flat as possible, and on the other side enables the heat pipe 115 to conform. In the embodiment shown, a contact surface facing the electrical component 130 is planar, and a groove-shaped depression is provided for contact at the first end of the heat pipe 115. In a similar manner to the system 100 of FIG. 1, the heat pipe 115 can be deformed in a controlled manner in order to enable the heat sink 205 to bear as flat as possible against the electrical component 130 when the cooling device 105 is attached to the assembly 110. In the present embodiment, the heat pipe 115 is preferably compressed between the heat sink 205 and the holding element 120 in a controlled manner until a predetermined deformation is reached. The travel control can be realized in particular by providing a spacer element 210 which is inserted between the cooling body 205 and the holding element 120 and, due to its size or vertical extent, delimits a minimum distance between the cooling body 205 and the holding element 120 in the downward direction.A tool 140 may be used to provide a required compressive force. Alternatively, the compressive force can be applied, for example, by means of a screw 215 which connects the cooling body 205 to the holding element 120 in the vertical direction. It is preferred that the spacer element 210 has a recess through which the screw 215 extends. It is further preferred that the screw 215 can be screwed into the holding element 120 from a side facing the assembly 110. For this purpose, the holding element 120 can comprise a blind hole in order to ensure a tightness in the region of the screw 215.In the lower portion of FIG. 2, the heat pipe 115 is deformed in a predetermined manner, and more specifically, compressed in the vertical direction. The cooling device 105 is attached to the assembly 110 and the optional cover 145 protects a bottom of the assembly 110.FIG. 3 shows a flow diagram of a method 300 for producing a system 100, in particular according to one of the embodiments of FIG. 1 or FIG. 2, The method 300 can be used, in particular, within the scope of a series production of systems 100 in order to individually adapt a generic cooling device 105 to a predetermined electrical assembly 110.In a step 305, an actual position of the component 130 relative to the carrier 125 can be determined. In particular, a deviation from the predetermined position 135 with respect to the carrier 125 can be determined.The deviation may include a vertical height above the carrier 125 and / or a tilt relative to the carrier 125.In a step 310, a deformation to which the first end of the heat pipe 115 of the cooling device 105 is to be exposed may be determined. The deformation usually comprises an elastic and a plastic part. The deformation is preferably determined in such a way that a contact surface of the heat pipe 115 or of the cooling body 205 on the component 130 is brought plastically, that is to say permanently, into a predetermined position with respect to the holding element 120.In a step 315, the heat pipe 115 is deformed in the manner determined in step 310. In one embodiment, the deforming is effected by means of a tool 140, in another embodiment by means of a screw 215 for attaching the cooling body 205 to the holding element 120.In a step 320, the heat pipe 115 with the holding element 120 is attached to the carrier 125 of the assembly 110. It should be noted that the deforming of the heat pipe 115 in step 315 and the attaching in step 320 may also be combined into a single step. For this purpose, the screw 215 can also serve for attaching the carrier 125 and / or the cover 145 to the holding element 120.Reference numerals denote reference numerals100 System 105 Cooling device 110 Assembly 115 Heat pipe 120 Holding member 125 Carrier 130 Component 135 Predetermined position 140 Tool 145 Cover 150 Heat conducting member 205 Heat sink 210 Spacer 215 Screw 300 Method 305 Determining position of the component relative to carrier 310 Determining required deformation 315 Heat pipe deform 320 Heat pipe with holding member attached to carrier

Claims

Cooling device (105) for an electrical assembly (110) having a carrier (125) to which a component (130) to be cooled is attached, wherein the cooling device (105) has the following elements: a heat pipe (115) having a first end which is configured to absorb heat; a holding element (120) for attaching the heat pipe (115) to the carrier (125) such that the first end of the heat pipe (115) is thermally coupled to the component (130); wherein the heat pipe (115) is configured to be deformed in the region of the first end in order to compensate for a deviation of a position of the component (130) from a predetermined position (135) with respect to the carrier (125); further comprising a cooling body (205) for bearing between the component (130) and the first end of the heat pipe (115); wherein the heat sink (205) may be attached to the support member (120) by a spacer, wherein a size of the spacer determines a position of the heat sink (205) relative to the support member (120).The cooling device (105) of claim 1, wherein the heat pipe (115) is compressible to a predetermined amount in the area of the first end.The cooling device (105) of claim 1 or 2, wherein the deformation is plastic.The cooling device (105) of any of the preceding claims, wherein the heat pipe (115) is located between the retaining element (120) and the structural element (130) when the cooling device (105) is attached to the carrier (125).Cooling device (105) according to one of the preceding claims, wherein a cross section of the undeformed heat pipe (115) in the region of the first end is round, oval or ellipsoidal.Cooling device (105) according to one of the preceding claims, wherein the structural element (130) has an abutment surface with a predetermined contour and the heat pipe (115) is configured to be deformed in the region of the first end in such a way that it abuts the abutment surface of the structural element (130).A system (100) comprising a cooling device (105) according to any of the preceding claims and an electrical assembly (110) having a carrier (125) and a component (130) attached to the carrier (125).A system (100) comprising a cooling device (105) according to any one of claims 1 to 6; and a plurality of spacers of different sizes for positioning the heat sink (205).A method (300) for manufacturing a system (100) comprising a cooling device (105) and an electrical assembly (110) having a carrier (125) and a component (130) attached thereto; wherein the cooling device (105) comprises a heat pipe (115) having a first end, which is configured to absorb heat, wherein the method comprises the steps of: determining (305) a deviation of a position of the component (130) from a predetermined position (135) with respect to the carrier (125); deforming (315) the heat pipe (115) in the region of the first end depending on the determined deviation; and attaching (320) the heat pipe (115) in a predetermined position with respect to the carrier (125), such that the first end of the heat pipe (115) is thermally coupled to the component (130).A method (300) of manufacturing a system comprising a cooling device (105) and an electrical assembly (110) having a carrier (125) and a component (130) attached to the carrier (125); wherein the cooling device (105) comprises a support member (120) and a heat pipe (115) having a first end configured to receive heat, the method comprising the steps of: determining (305) a deviation of a position of the component (130) from a predetermined position (135) with respect to the carrier (125); selecting (310) a spacer whose size corresponds to the determined deviation; placing (310) the spacer (210) between a heat sink (205) and the support member (120); deforming (315) the first end of the heat pipe (115) until the spacer (210) abuts between the heat sink (205) and the retaining member (120); and attaching (320) the retaining member (120) to the carrier (125) such that the first end of the heat pipe (115) is thermally coupled to the component (130).

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