Cooling system for cooling an electrical assembly and a driver assistance system with such a cooling system

Abstract

Cooling system (100) for cooling an electrical assembly, comprising a cooler (115) with a recess (125) for receiving a connection section (130) of a heat sink (135), wherein the heat sink (135) further comprises a receiving section (140) configured to spatially receive a chip (105) of the electrical assembly and to be connected to a printed circuit board (110) bonded to the chip (105), wherein the printed circuit board (110) has at least one recess (155) through which a projection (145) of the receiving section (140) is passed, wherein means for fixing the heat sink (135) to the cooler (115) are provided on the projection (145), wherein the connection section (130) of the heat sink (135) has a substantially round cross-section, and wherein the connection section (130) of the heat sink (135) has a circumferential groove. (170) for receiving a sealing element.

Description

[0001] The present invention relates to a cooling system for cooling an electrical assembly. Furthermore, the invention relates to a driver assistance system (abbreviated FAS, in English "Advanced Driver Assistance Systems" or ADAS) comprising such a cooling system.

[0002] From DE 10 2020 203 879 A1, a cooling system for an electrical assembly with a component to be cooled is known. The cooling system comprises a cooling channel for receiving a cooling fluid and a heat sink that extends axially through a recess in the cooling channel. The cooling channel is designed to be attached to the assembly such that an axial end of the heat sink is located in the area of ​​the component. A device is provided for exerting an axial force to drive the heat sink out of the recess and press the heat sink axially against the component.

[0003] DE 10 2022 213 806 A1 discloses a cooling arrangement, a control device, a control device system and a manufacturing process.

[0004] One object of the invention is to provide a cooling system for cooling an electrical assembly that is easier and safer to install. The invention achieves this object by means of the subject matter of the independent claims. Dependent claims describe preferred embodiments.

[0005] A cooling system according to the invention for cooling an electrical assembly comprises a cooler with a recess for receiving a connection section of a heat sink, wherein the heat sink further comprises a receiving section which is configured to spatially receive a chip of the electrical assembly and to be connected to a printed circuit board which is materially bonded to the chip component, wherein the printed circuit board has at least one recess through which a projection of the receiving section is passed, wherein means for fixing the heat sink to the cooler are provided on the projection of the receiving section.

[0006] The cooler is designed to receive a cooling medium, in particular a liquid cooling medium or coolant, and to guide it through designated channels, lines, pipes, or the like. The cooler serves to cool the electrical assembly or to absorb and dissipate heat from the electrical assembly. The cooler has channel sections which, when the cooling system is installed (i.e., when the heat sink is positioned in the recess), are fluidically connected to channel sections of the heat sink. Accordingly, the heat sink, once installed in the cooler, is also designed to receive and guide a cooling medium.

[0007] The heat sink consists of several sections, including the connection section for attaching the heat sink to the cooler and the receiving section for holding the chip. The connection section and the receiving section can be joined together as a single piece. The connection section is designed to correspond to the recess in the cooler. In other words, the outer geometry of the heat sink is complementary to the inner geometry of the cooler's recess, such that the heat sink can be inserted or pressed into the recess in one mounting direction, essentially axially.

[0008] The heat sink's mounting section is designed for the mechanical connection of the heat sink to the chip. The chip is understood to be an electrical assembly or part of an electrical assembly that is to be cooled by the cooling system. The chip is arranged on the circuit board such that, if the chip is bonded to the circuit board and is located within an interior space of the mounting section, the space in which the chip is located is spatially delimited by the mounting section and the circuit board.

[0009] Preferably, the chip is soldered onto the printed circuit board (PCB). A connection layer of the chip is electrically connected to the PCB. This connection layer can be a ball grid array (BGA) located on the side of the chip facing the PCB. The BGA consists of small solder beads arranged side-by-side in a grid of columns and rows. These beads are melted by a soldering process and connect to contact pads on the PCB.

[0010] After the material bonding, the chip and the circuit board form a separately manageable unit that can be attached to the heat sink or the receiving section of the heat sink when mounting the cooling system.

[0011] After the connecting section is inserted or pressed into the recess of the cooler, the circuit board is preferably screwed to the receiving section of the heat sink. The heat sink is first connected to the circuit board and the chip mounted on it before the heat sink is inserted into the recess of the cooler.

[0012] Preferably, the recess in the cooler is designed such that the heat sink must be pressed into the recess during assembly of the cooling system. In other words, after the heat sink is mounted to the cooler, there is an interference fit between the cooler and the heat sink. This creates a secure and permanent connection between the heat sink and the cooler. The pressing action can be performed using a separate pressing tool, which presses the heat sink into the supported cooler. Pressing continues until the heat sink is flush against the cooler.

[0013] The respective protrusion of the receiving section is designed and configured to minimize forces acting on the circuit board and, if applicable, the chip during the pressing of the heat sink into the cooler. This protrusion acts as a support, extending through the circuit board and contacting it with the circuit board during the pressing process using the aforementioned pressing tool. Thus, the mechanical forces are not transferred to the circuit board and, if applicable, the solder joint between the chip and the circuit board, but are instead transferred directly to the heat sink via the respective protrusion.

[0014] Preferably, several projections are provided on the receiving section, which extend axially through corresponding recesses in the printed circuit board. This enables the heat sink to be pressed evenly into the cooler. In particular, this reduces the mechanical stress during the assembly of the cooling system between the heat sink and the chip, between the heat sink and the printed circuit board, and between the printed circuit board and the cooler.

[0015] Preferably, the means for fixing the heat sink comprise an opening oriented in the mounting direction of the heat sink, through which a screw can be passed to fix the connection section of the heat sink to the cooler. The opening can be a bore for the passage of a screw or threaded bolt to bolt the heat sink to the cooler during installation of the cooling system. For this purpose, the cooler has corresponding internal threaded bores that are designed to be complementary to the screw. The screwing action can assist the press-fit process. If there are multiple projections, several openings or bores are provided, each through which a screw can be passed. The screws have corresponding screw heads that bear against the associated projection.

[0016] The cooling system described herein reduces the thermal resistance between the chip and the cooler. Furthermore, additional interfaces that could increase thermal resistance can be avoided, especially if the chip is designed without a cover.

[0017] Preferably, the printed circuit board (PCB) is used. A PCB (Printed Circuit Board) is an electrical circuit consisting of an insulating material with conductive traces. A PCB serves to mechanically mount electronic components and connect them electrically. Components such as sensors, resistors, capacitors, transistors, and / or integrated circuits can be mounted on a PCB to create an electronic circuit. The conductive traces on the PCB allow electrical current to flow between the components and connect them to other PCBs or components.

[0018] The chip is preferably a system-on-a-chip (SoC) component. So-called systems-on-a-chips (SoCs) typically consist of at least one microprocessor, a bus system comprising one or more buses, interfaces to external storage, input / output components, graphics units, and optionally other peripherals. An SoC chip is an integrated circuit on which a multitude of functions of an electronic system are combined. Essentially, it is a complete system housed on a single chip. Integrating these functions onto a single chip saves space and improves system efficiency. Overall, an SoC chip enables a compact and powerful solution for electronic systems by combining a multitude of functions on a single chip. The SoC component is preferably designed without a lid.The SoC component features a ring element that can be used to stiffen and / or axially support the chip on the heatsink's mounting surface, particularly during assembly. To compensate for any tolerances between the chip and the heatsink, a thermally conductive material, such as a pad, can be placed between the chip and the mounting surface of the heatsink's mounting surface to ensure good thermal contact between the chip and the heatsink. This makes the cooling system particularly well-suited for high-performance SoCs.

[0019] According to the invention, the connection section of the heat sink has a substantially round cross-section. The connection section of the heat sink also features a circumferential groove for receiving a sealing element. The sealing element is preferably designed as an O-ring, with the groove being configured to receive the O-ring. The round, and in particular circular, design of the connection section of the heat sink, combined with the sealing element, especially the O-ring, can be used to eliminate assembly tolerances of the cooling system by pressing the heat sink, together with the circuit board and the chip mounted on it, into the cooler as a separately manageable unit. The seal provided by the sealing element can flexibly compensate for variations in the height of the connection section, since the sealing element seals at any desired position during pressing.

[0020] In a further development of the invention, the circuit board is fixed to the cooler. After the heat sink has been mounted or pressed onto the cooler, the circuit board can be additionally fixed to the cooler, in particular by a screw connection.

[0021] An assembly method for mounting the cooling system may comprise the following steps: attaching the heat sink to the circuit board, or vice versa, in particular by screwing; pressing the heat sink with the circuit board attached to it into the recess of the cooler using an assembly tool until the heat sink comes to rest against an end face of the cooler, the assembly tool being supported by the respective projection; fixing the heat sink to the cooler, in particular by screwing. The screwing includes at least one screw connection between the two components to be screwed together.

[0022] A driver assistance system according to the invention for a motor vehicle comprises an electrical assembly that can be cooled by means of a cooling system described herein. Driver assistance systems are electronic add-ons in motor vehicles to support the driver in certain driving situations. Safety aspects, but also the increase of driving comfort, are often paramount. The driver assistance system in question is, in particular, a driver assistance system according to Level 3 of the automation level classification according to the SAE J2016 standard, which describes the classification and definition of terms for road-bound motor vehicles with automated driving systems.

[0023] The invention will now be described in more detail with reference to the attached figures, in which: Fig. 1 a first highly schematic sectional view of a cooling system according to the invention for cooling an electrical assembly before assembly; and Fig. 2 a second highly schematic sectional view of the cooling system according to the invention Fig. 1 after assembly, where identical or similar components are marked with the same reference numeral.

[0024] The Fig. 1 and Fig. Figure 2 shows a cooling system 100 according to the invention for cooling an electrical assembly in different assembly states. Fig. Figure 1 shows the cooling system 100 in its unassembled state or at the beginning of assembly. Fig. Figure 2 shows the cooling system 100 in its assembled state or after assembly.

[0025] This assembly comprises a chip 105 designed as a system-on-a-chip (SoC) component, which is soldered onto a printed circuit board 110. After the metallurgical bonding and before the installation of the cooling system 100, the chip 105 and the printed circuit board 110 form a separately manageable unit. The cooling system 100 is intended for a driver assistance system according to the invention (not shown here), which can be used in a motor vehicle.

[0026] The cooling system 100 comprises a cooler 115 through which a liquid cooling medium is guided in channels 120. One of these cooling medium-carrying channels 120 is located in the Fig. 1 and Fig. Figure 2 is shown as an example. The cooler 115 has a recess 125 for receiving a connection section 130 of a heat sink 135. The recess 125 has a substantially circular cross-sectional geometry. Accordingly, the connection section 130 of the heat sink 135 also has a cross-sectional geometry that is complementary to the recess 125 and circular in shape.

[0027] On the side of the connection section 130 facing away from the cooler 115, a receiving section 140 of the heat sink 135 is arranged and integrally connected to the connection section 130. The receiving section 140 is hollow and designed to spatially accommodate the chip 105 and to be connected to the printed circuit board 110 when the cooling system 100 is installed. In this example, the receiving section 140 has two projections 145 on an end face facing away from the cooler, which are designed to receive the printed circuit board 110. Thus, the printed circuit board 110 can be threaded onto or slid onto the projections 145.

[0028] In an assembly process, the unit consisting of chip 105 and circuit board 110 is first positioned on the receiving section 140 of the heat sink 135, wherein the chip 105 is inserted axially into the interior of the receiving section 140 until a ring element 150 of the chip 105 comes into axial contact with the receiving section 140. A thermally conductive material 152 is provided between the chip 105 and the receiving section 140 to ensure good thermal contact between the chip 105 and the receiving section 140 of the heat sink 135.

[0029] The printed circuit board 110 has two recesses 155 arranged on the board such that a corresponding projection 145 of the receiving section 140 can pass through them. This allows the printed circuit board 110 with the chip 105 to be positioned relative to the receiving section 140. Each recess 155 has a geometry complementary to the corresponding projection 145. The printed circuit board 110 is fixed to the receiving section 140 of the heat sink 135 by two screws 160, so that the unit consisting of the chip 105 and the printed circuit board 110, together with the heat sink 135, now forms a separately manageable unit before this unit is inserted into the cooler 115.

[0030] The heat sink 135 is then pressed into the recess 125 of the cooler 115 in the mounting direction 165. An assembly tool (not shown) is positioned on the projections 145, and this tool applies the force required to press the heat sink 135 into the recess 125. The recess 125 is thus designed such that the heat sink 135 must be pressed into the recess during the assembly of the cooling system 100, resulting in an interference fit after assembly.

[0031] A sealing effect is achieved after assembly by means of a sealing element 175, which is an O-ring and is arranged in a circumferential groove 170 of the connection section 130. The first arrow 200 points vertically downwards and the second arrow 205 points vertically upwards. Fig.Figure 2 is intended to illustrate that after pressing the heat sink 135 into the cooler 115, a fluidic connection exists between the channel 120 of the cooler 115 and channels of the heat sink 135 (not shown here), so that heat generated by the chip 105 during operation can be absorbed and dissipated by the material of the heat sink 135 or the cooling medium contained therein.

[0032] At each projection 145 of the receiving section 140, an opening 180 in the form of a through-hole is provided, aligned in the mounting direction 165 of the heat sink 135, as a means of fixing the heat sink 135 to the cooler 115. A second screw 185 can be passed through each opening 180 to fix or screw the connection section 130 of the heat sink 135 to the cooler 115. After the heat sink 135 has been pressed into the cooler 115, the circuit board 110 is additionally fixed to the cooler 115, in this case by means of at least one third screw 190. Reference sign 100 Cooling system 105 Chip 110 circuit boards 115 coolers 120 channels 125 recess 130 Connection section of the heat sink 135 heat sinks 140 Receptacle of the heat sink 145 lead 150 ring element of the chip 152 thermally conductive mass 155 Cutout in the circuit board 160 First screw 165 Mounting direction of the heat sink 170 Nut 175 Sealing element 180 Breakthrough 185 Second screw 190 Third screw 200 First Arrow 205 Second Arrow

Claims

[1] Cooling system (100) for cooling an electrical assembly, comprising a cooler (115) with a recess (125) for receiving a connection section (130) of a heat sink (135), wherein the heat sink (135) further comprises a receiving section (140) which is configured to spatially receive a chip (105) of the electrical assembly and to be connected to a printed circuit board (110) which is metallurgically bonded to the chip (105), wherein the printed circuit board (110) has at least one recess (155) through which a projection (145) of the receiving section (140) is passed, wherein means for fixing the heat sink (135) to the cooler (115) are provided on the projection (145), wherein the connection section (130) of the heat sink (135) has a substantially round cross-section, wherein the connection section (130) of the heat sink (135) has a circumferential groove (170) for receiving a sealing element. [2] Cooling system (100) according to claim 1, wherein the means for fixing the heat sink (135) comprise an opening (180) aligned in the mounting direction (165) of the heat sink (135) through which a screw (185) can be passed to fix the connecting section (130) of the heat sink (135) to the cooler (115). [3] Cooling system (100) according to claim 1 or 2, wherein the circuit board (110) is screwed to the receiving section (140) of the heat sink (135). [4] Cooling system (100) according to one of the preceding claims, wherein the printed circuit board (110) is a PCB printed circuit board. [5] Cooling system (100) according to one of the preceding claims, wherein the chip (105) is soldered onto the circuit board (110). [6] Cooling system (100) according to one of the preceding claims, wherein the chip (105) is a system-on-a-chip component. [7] Cooling system (100) according to one of the preceding claims, wherein the recess (125) of the cooler (115) is designed such that the cooling element (135) must be pressed into the recess during the assembly of the cooling system. [8] Cooling system (100) according to one of the preceding claims, wherein the circuit board (110) is fixed to the cooler (115). [9] Driver assistance system for a motor vehicle, comprising an electrical assembly which can be cooled by means of a cooling system (100) according to one of the preceding claims.

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