Cooling case and cold plate structure for cooling a printed circuit board

Abstract

To provide a cooling case and cold plate capable of lowering temperature rise even with high thermal load.SOLUTION: A printed circuit board cold plate (cooling plate) structure consists of a cooling case 10 that internally cools the printed circuit board (PCB) with air or fluid and a slot 11 that is located in the case 10 and opens into the relevant board area of the case 10, transfers heat to the chassis (case) wall, and removes high thermal loads from a cold plate 20. It also eliminates the need for a wedge mechanism.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a cooling case that cools a printed circuit board (PCB) with air or fluid inside, and a cold plate structure that is disposed in the case and is composed of slits that open into a related substrate region of the cooling case, transfers heat to the chassis (case) wall, and eliminates the need for a wedge mechanism.

Background Art

[0002] A printed circuit board (PCB) needs to be mechanically fixed to a machine for cooling purposes and to meet the mechanical and electrical requirements in military electronic component packaging. Mechanically, the printed circuit board needs to be resistant to shock and vibration, and electrically, it is necessary to combine the required connectors with each other. In particular, cooling a substrate with a very high heat load by a heat conduction method provides great advantages for many platforms. There may be two or more substrates in one case. If one or more of these substrates have an excessive heat load compared to other substrates, the entire cooling architecture can be changed.

[0003] In the prior art, an electronic substrate (PCB) is used with a wedge mechanism. This structure is externally connected to each other and attached to the case by sliding from the upper region. Due to the gaps and interfacial resistance inside the used wedge lock mechanism, this structure produces a high thermal resistance. The biggest problem with the prior art is that the thermal resistance is 0.2 °C / W for hollow mechanical parts and 0.5 °C / W for the wedge lock surface. In this case, heat cannot be evenly distributed, and the combined thermal resistance that is radiated simultaneously varies from 0.143 to 0.2 °C / W. In such a situation, if a heat load of 70 W is transmitted only from one wall through the wedge mechanism, a temperature rise of 10 °C may occur through this transfer.

[0004] Patent Document 1 (US4962444A) relates to a cooling system comprising a chassis having a cold rib (cooling rib) for cooling an electronic substrate within an electronic system. Without changing the prior art cold plate (cooling plate) attachment method, a new and effective fluid path has been designed such that the cooling fluid can reach the edge of the cold plate. However, there is no configuration that eliminates the interfacial thermal resistance between the cold plate and the case, enables attachment without a substrate holder, and eliminates the thermal resistance from the substrate holder.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] As a result, due to the above-mentioned drawbacks and the inadequacy of existing solutions regarding the subject matter, improvements in the related technical fields are needed.

Problems to be Solved by the Invention

[0007] This invention is triggered by the present invention and aims to solve the above-mentioned problems.

[0008] [Object of the Invention] The main object of the present invention is to provide a cooling case and a cold plate that can attach the cold plate to the cooling case by sliding from the side wall without extending the fluid or air path, thereby enabling a low temperature rise even under a high heat load.

[0009] Another object of the present invention is to bring the coolant of the cooling case into contact with the cooling fins arranged at the edge of the cold plate.

[0010] A further object of the present invention is to provide a cold plate flange for sealing that fits into the cooling case by means of screws and gaskets.

[0011] A further object of the present invention is to provide an embodiment that does not utilize a wedge mechanism and thus does not have the high thermal resistance caused by the gaps and interface resistance inside the wedge lock mechanism when used.

Means for Solving the Problems

[0012] To achieve the above object, the present invention is a cooling structure for a printed circuit board, wherein the printed circuit board is fixed inside to meet both cooling requirements and mechanical and electrical requirements. The cooling structure includes: · a cold plate; and · a cooling case that provides cooling by air or fluid and in which the cold plate is disposed, and includes: · at least one plate slot opened on a side portion of the cooling case, through which the cold plate can be inserted into the cooling case; and · fins configured to be on a side portion of the cold plate corresponding to the plate slot, which enables removing a high heat load from the cold plate. It is characterized by comprising the above.

[0013] The structural and characteristic features and all advantages of the present invention will be more clearly understood from the drawings given below and the detailed description described with reference to these drawings. Therefore, the evaluation should be made with reference to these drawings and the detailed description.

Brief Description of the Drawings

[0014]

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[0015] <Description of reference signs> 1 Printed circuit board 2 Wedge lock mechanism 10 Cooling case 11 Plate slot 20 Cold plate 21 Fin 22 Outer cover 23 Outer cover gasket 24 Case gasket 25 Screw 26 Thermal interface material

Best Mode for Carrying Out the Invention

[0016] In this detailed description, the preferred embodiments of the cooling case and cold plate of the present invention are described only for better understanding of the gist.

[0017] In the present invention, embodiments are provided that improve heat conduction cooling to meet other requirements by conventionally known methods. In this embodiment, a method has been developed to minimize the heat performance loss caused by the wedge mechanism of a substrate having a very high heat load. In this method, slots open into the associated substrate region of the case, and a plate called a cold plate is inserted into the case from the outside. The cold plate is used to transfer heat from the electronic element to the chassis (case) wall. In an embodiment of the gist of the present invention, the wedge mechanism is completely eliminated. The edge of the slide plate is kept wide, fins are added to improve the cooling efficiency, and a gasket is added to the flange of the slide plate to ensure sealing. Also, in both the case of a fluid-cooled case and an air-cooled case, the aim is to obtain a structure that is extremely efficient, easy to manufacture, and thermally advantageous.

[0018] In the most basic form, the configuration of the cooling case (10) and the cold plate (20) of the present invention for cooling the printed circuit board (1) includes a fluid-cooled or air-cooled case (10) and a cold plate (20) disposed within the cooling case (10).

[0019] The most important feature that distinguishes the embodiment of the gist of the present invention from the prior art is the opening of the plate slot (11) on the side of the cooling case (10). The plate slot (11) allows the cold plate (20) to be inserted into the cooling case (10) from the side. Further, heat is directly removed from the wall surface of the cooling chassis by fins (21) configured to be on the side of the cold plate corresponding to the plate slot, whereby a high heat load is removed from the cold plate.

[0020] In an embodiment of the subject matter of the present invention, there is at least one outer cover (22) that closes the opening of the cold plate (20) entering the cooling case (10), and this opening is the plate slot (11). Also, to ensure sealing, there is also an outer cover gasket (23) configured to be between the fins (21) and the outer cover. Embodiments of the present invention further include a case gasket (24) for sealing configured to be between the fins (21) and the cooling case (10). In this specification, the outer cover (22) is fixed to the cooling case (10), and the sealing is completed by screws and the outer cover gasket (23). Further, a thermal interface material (26) is provided on the side wall of the cold plate (20). The thermal interface material (26) reduces the thermal resistance of the side wall of the cold plate (20).

[0021] In an embodiment of the gist of the present invention, the PCB or element to be cooled and the cold plate (20) are connected to each other by screws and move together. By changing the material of the cold plate (20), the thermal conduction resistance to the edge of the substrate can be managed. However, the wedge mechanism is the biggest problem in heat transfer from the cold plate to the case. The wedge structure is practical and provides convenience in disassembly and assembly, but causes very serious problems in cooling. In fact, the substrate will not be disassembled unless there is a problem, but as long as the wedge mechanism exists, the substrate must always operate at a high temperature. This problem has been grasped, and with the structure of the present invention, the substrate can be installed together with or separately from the cold plate. At one edge, the heat conduction to the coolant continues without interruption, and at the same time, at the other edge, by pressing the case edge with a large surface, the encountered thermal resistance becomes very low compared to the conventional wedge structure. As a result, the product becomes cooler, the performance becomes higher, and the lifespan becomes longer.

[0022] Figure 1 shows the assembly of a printed circuit board (1) into a cooling case equipped with a wedge lock mechanism (2). Here, the wedge mechanism is used not for heat transfer but for connecting the board to the case. The cold plate of the board itself on the board is designed flat so that heat can be conducted to a slide-type cold plate (20). Then, with the help of the wedge mechanism to facilitate disassembly and assembly, the board can be disassembled and assembled.

[0023] Figures 3 and 4 show from above two different mechanisms, namely, a cold plate (2) having a wedge lock mechanism (2) inside a cooling case (10) and the slide-type cold plate (20) of the present invention. By improving the cooling by 8 - 10 °C, it becomes possible to reduce the volume of the cooling unit (exchanger) used in a fluid cooling system by up to half.

[0024] Figures 7 and 8 show the differences in heat conduction paths by two different cooling methods. In the structure of the wedge mechanism, heat is divided into two separate lines, but there are losses due to the interface between metals and resistance in the wedge mechanism. In an embodiment of the gist of the present invention, heat reaches the cooling fins (21) of the cold plate (20). Further, by pressing the wall of the cooling case (10) from a large surface, this surface also transfers a part of the heat to the case wall. Simply providing a gasket structure on one side of the plate is sufficient to take sealing measures on one side.

[0025] Since the cold plate (20) is on the cooling fins (21), it is in direct contact with the cooler, and there is no performance degradation of 10 - 11 °C that may occur in a board with a total heat load of 100 - 120 W, which would occur in other methods. Further, it is very practical for disassembling and assembling the board. Further, since sealing means are provided, the same structure can be easily used in either an air-cooled structure or a fluid-cooled structure.

Claims

1. A cooling structure for a printed circuit board (1), wherein the printed circuit board (1) is fixed inside to meet both cooling requirements and mechanical and electrical requirements. The cooling structure comprises: - a cold plate (20), and - a cooling case (10) that provides cooling by air or fluid and in which the cold plate (20) is disposed, - at least one plate slot (11) opened on a side portion of the cooling case (10), through which the cold plate (20) can be inserted into the cooling case. The cooling structure further comprises the plate slot (11), - fins (21) configured to be on a side portion of the cold plate (20) corresponding to the plate slot (11). The fins (21) directly remove heat from the wall surface of the cooling case (10) and enable removal of a high heat load from the cold plate (20). The cooling structure further comprises the fins (21), - a case gasket (24) for sealing configured to be between the fins (21) and the cooling case (10), characterized in that it comprises the above components. A cooling structure for a printed circuit board (1).

2. A cooling structure for a printed circuit board (1) according to Claim 1, comprising at least one outer cover (22) for closing an opening of the cold plate (20) entering the cooling case (10), wherein the opening is the plate slot (11). The cooling structure is characterized by this.

3. A cooling structure for a printed circuit board (1) according to Claim 2, comprising an outer cover gasket (23) for sealing configured to be between the fins (21) and the outer cover (22). The cooling structure is characterized by this.

4. A cooling structure for a printed circuit board (1) according to Claim 2, comprising at least one screw (25) for fixing the outer cover (22) to the cooling case (10) to complete the sealing. The cooling structure is characterized by this.

5. A cooling structure for a printed circuit board (1) according to Claim 1, comprising a thermal interface material (26) disposed on a side wall of the cold plate (20) to reduce thermal resistance. The cooling structure is characterized by this.

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