A power module and packaging method integrating three-dimensional stacked manifold microchannel cooling

Abstract

The application discloses a power module integrated with three-dimensional stacked manifold micro-channel cooling, which comprises a copper-clad ceramic plate, a chip and a heat sink arranged on the upper and lower sides of the copper-clad ceramic plate, the heat sink comprises a micro-channel layer with a micro-channel structure arranged on the copper-clad ceramic plate, and a manifold layer covering the micro-channel structure, the manifold layer comprises a grid structure composed of a plurality of manifold walls and baffles, two adjacent grids in the grid structure and the micro-channel structure form a cooling channel for the up-and-down flow of coolant, and the heat sink is arranged above the chip during use. The application further provides a packaging method of the power module. The device provided by the application can improve the heat dissipation efficiency and stability of the semiconductor device.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device heat dissipation packaging, and particularly relates to a power module and packaging method with integrated three-dimensional stacked manifold microchannel cooling. Background Technology

[0002] Liquid cooling of power electronic devices has been a well-established technology for many years. Every electronic circuit generates heat due to conduction and switching losses in power components and ohmic losses in conductor tracks. As the power density of power electronic devices continues to increase, cooling efficiency is receiving increasing attention.

[0003] Cooling efficiency is highly relevant because each new generation of power semiconductors tends to be smaller than the previous one, and the market constantly demands smaller and more compact solutions. Therefore, adequate cooling of power electronic devices is crucial. Due to the high thermal conductivity of liquids, liquid cooling is superior to air cooling. Consequently, liquid cooling is finding increasing applications.

[0004] Traditional cooling structures have low heat dissipation efficiency, mainly due to their simple flow patterns and fixed directions, which leads to high thermal resistance. This traditional heat dissipation method typically uses conventional pin-fin or S-shaped shunt channels, which cannot meet the heat dissipation requirements of high-power-density chips.

[0005] In traditional cooling methods, the water temperature gradually rises along the flow direction, resulting in significant junction temperature differences between multiple chips and uneven current distribution among them. This uneven current distribution can further exacerbate the thermal differences between power chips, thus affecting system performance and reliability. Because traditional cooling methods cannot meet the cooling requirements of high-power chips, this uneven current distribution problem is particularly severe in high-power chips.

[0006] Traditional chip layout and heat sink design are independent of each other, and the heat sink structure has poor flexibility, making it difficult to carry out personalized heat dissipation design for different chip layouts, thus limiting the heat dissipation performance and overall efficiency of the heat sink.

[0007] Patent document CN114514606A discloses a cooling system including a serpentine path. This cooling system comprises a cooling arrangement having a serpentine path for circulating fluid coolant, the serpentine path being disposed between multiple walls that are displaced relative to each other. A series of baffles, each having a proximal portion and a distal portion, are disposed within the path. The baffles extend from one of the walls into the path. The width of the distal portion is greater than the width of the proximal portion. However, this method suffers from the problem that the temperature of the fluid coolant at the beginning of the path is lower than the temperature at the end, resulting in different cooling efficiencies for the chips at different points.

[0008] Patent document CN112534573A discloses a flow distributor for cooling electrical components, which distributes a flow of heat-transmitting fluid from the electrical components across a surface cooled and / or heated by the fluid. The distributor includes at least one flow channel configured to guide the fluid flow across the surface, these flow channels being defined on both sides by walls to form a path for the fluid flow within these flow channels, and including wall segments extending into the at least one flow channel; and at least one of these wall segments includes at least one bypass passage to connect two adjacent spaces separated by the wall segment, wherein the at least one bypass passage extends from one side of the wall segment to the other side in an inclined orientation to establish a short-circuit flow for a portion of the fluid flow. This fluid distributor only targets global cooling of the power chip; however, in practical situations where only localized areas experience high temperatures, this structure can easily affect the flow efficiency of the coolant. Summary of the Invention

[0009] The purpose of this invention is to improve traditional heat dissipation structures, thereby enhancing the heat dissipation efficiency and stability of semiconductor devices.

[0010] To achieve the objectives of this invention, a power module with integrated three-dimensional stacked manifold microchannel cooling is provided, comprising a copper-clad ceramic plate, and chips and a heat sink arranged on the upper and lower sides of the copper-clad ceramic plate. The heat sink includes a microchannel layer with a microchannel structure arranged on the copper-clad ceramic plate, and a manifold layer covering the microchannel structure. The manifold layer includes a grid structure composed of multiple manifold walls and baffles. Adjacent grids in the grid structure, together with the microchannel structure, form cooling channels for the vertical flow of coolant. In use, the heat sink is positioned above the chips.

[0011] This invention employs a cooling channel composed of multiple grids and microchannel structures, which allows the coolant to flow in a U-shape within the heat sink to extend the heat dissipation path. At the same time, it ensures that the coolant temperature and flow rate are consistent within each microchannel, thereby effectively absorbing the heat from the chip.

[0012] Specifically, the grid structure of the manifold layer is adjusted according to the distribution of heat-generating parts of the chip: for parts of the chip that heat up quickly in a localized manner, the number of grids is increased to improve the flow rate of the coolant, thereby adaptively improving the heat dissipation efficiency and solving the defects of traditional uniform convection heat dissipation.

[0013] Specifically, the grid structure is constructed by setting multiple baffles between two adjacent manifold walls. The more baffles there are, the faster the coolant flows at that location.

[0014] Specifically, the manifold wall and the microchannel structure are arranged in an alternating vertical arrangement.

[0015] Specifically, the angle range of the staggered arrangement of the manifold wall and the microchannel is 30° to 90°.

[0016] The present invention also provides a packaging method for a power module, used to fabricate the above-mentioned integrated three-dimensional stacked manifold microchannel cooling power module, comprising:

[0017] Step 1: Based on the size of the copper-clad ceramic substrate and the chip arrangement, prepare microchannel layers and manifold layers of corresponding sizes.

[0018] Step 2: Polish the microchannel structure in the microchannel layer and the grid in the manifold layer.

[0019] Step 3: Print nano-silver paste on the microchannel structure contact surface between the manifold layer and the microchannel layer using a silver film transfer process, and perform hot pressing treatment using a pressure silver sintering device to obtain the heat sink.

[0020] Step 4: The heat sink and copper-clad ceramic plate are packaged sequentially using silver sintering process, and the copper-clad ceramic plate and chip are packaged together. At the same time, the input and output terminals of the chip are connected by soldering.

[0021] Specifically, the surface horizontal deviation between the microchannel structure of the microchannel layer and the manifold layer is 1 to 20 micrometers.

[0022] Specifically, in step 4, the welding methods include reflow soldering and ultrasonic soldering.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] Compared to traditional pin-fin and S-shaped flow channels, the U-shaped flow channel constructed by the microchannel and manifold layer provided by this invention can make the coolant temperature and flow rate in each microchannel consistent, reducing the junction temperature difference between chips, thereby improving the heat dissipation efficiency and reliability of the chip. Attached Figure Description

[0025] Figure 1 This is a frontal view of the power module provided in this embodiment;

[0026] Figure 2 This is a schematic diagram of the power module from the rear view provided in this embodiment;

[0027] Figure 3 This is a partially enlarged schematic diagram of the heat sink provided in this embodiment;

[0028] Figure 4 This is a schematic diagram of the second type of grid structure for the manifold layer provided in this embodiment;

[0029] Figure 5 This is a schematic diagram of the third type of grid structure for the manifold layer provided in this embodiment;

[0030] Figure 6 A flowchart of the encapsulation method provided in this embodiment;

[0031] Figure 7 This is a temperature comparison diagram between the power module and a traditional power module provided in this embodiment;

[0032] Figure 8 This is a comparison diagram of the inlet pressure between the power module and a traditional power module provided in this embodiment;

[0033] Figure 9 This embodiment provides a graph showing the relationship between the number of baffles and the temperature of the power module and the inlet pressure.

[0034] In the diagram, 1. Manifold layer; 2. Microchannel layer; 3. Chip; 4. Copper-clad ceramic plate; 5. Baffle; 6. Manifold wall; 7. Microchannel. Detailed Implementation

[0035] like Figure 1 and Figure 2 As shown, this example provides a power module including a copper-clad ceramic plate 4, a chip 3 and a heat sink arranged on and below the copper-clad ceramic plate 4. The heat sink includes a microchannel layer 2 with a microchannel structure and a manifold layer 1. In addition, an inlet and an outlet are respectively provided on both sides of the manifold layer to facilitate the flow of coolant.

[0036] More specifically, such as Figure 3 As shown, the microchannel structure consists of multiple microchannels 7 arranged in parallel on the surface of the microchannel layer 2. The manifold layer 1 includes a grid structure formed by multiple equally spaced manifold walls 6 and baffles 5 connected together. The manifold walls 6 and the microchannels 7 below are arranged in an alternating manner with an included angle of 90°. Multiple grids are divided between two adjacent manifold walls 6 by multiple baffles 5, and two adjacent grids and the multiple microchannels 7 below form a U-shaped cooling channel. After the coolant enters the manifold layer 1, it can fill the multiple microchannels 7 below in an equal amount based on the manifold walls 6 and baffles 5. At the same time, the denser arrangement of baffles 5 can promote the flow rate of coolant at the corresponding position, thereby accelerating the heat dissipation efficiency of the corresponding area and improving the local heat dissipation efficiency.

[0037] like Figure 4 and Figure 5 As shown, this is a grid structure extended based on the technical solution provided in this embodiment.

[0038] Figure 4 The baffles 5 are arranged at equal intervals, and the staggered angle between the manifold wall 6 and the microchannel 7 is 90°, which facilitates mass production and is suitable for heat dissipation tasks of ordinary chips.

[0039] Figure 5 The staggered angle between the manifold wall 6 and the microchannel 7 is 30°, so that the four manifold walls 6 connected end to end form a rhombus grid. At the same time, the baffle 5 connects the adjacent rhombus grids in series. The rhombus grid divides the microchannel 7 below into different lengths, thereby realizing the adjustment of the coolant flow rate at different positions. It is suitable for use in chips with localized heat generation in specific locations.

[0040] In addition, this embodiment can use a double-sided heat sink arrangement to dissipate heat from the power chip.

[0041] This embodiment also provides a packaging method for fabricating the power module proposed in the above embodiments, such as... Figure 6 As shown, it includes the following steps:

[0042] Step 1: Based on the size of the copper-clad ceramic substrate and the chip arrangement, prepare microchannel layers and manifold layers of corresponding sizes.

[0043] Step 2: Polish the microchannel structure in the microchannel layer and the grid in the manifold layer to ensure surface flatness and remove the oxide layer. The surface levelness deviation of the microchannel layer and the manifold layer should be less than 20 micrometers.

[0044] Step 3: Print nano-silver paste on the contact surface of the microchannel structure between the manifold layer and the microchannel layer using a silver film transfer process, and sinter the manifold layer and the microchannel layer into a whole using a pressure silver sintering device to obtain a heat sink.

[0045] Step 4: The heat sink and copper-clad ceramic plate are packaged sequentially using silver sintering process, and the copper-clad ceramic plate and chip are packaged together. At the same time, the input and output terminals of the chip are connected by soldering.

[0046] In addition, radiators can also be assembled by welding.

[0047] To demonstrate the heat dissipation effect of the power module provided in this embodiment, such as Figure 7 As shown, under the same power output conditions, the heat sink provided in this embodiment can effectively reduce the operating temperature of the chip.

[0048] like Figure 8 As shown, the inlet pressure of the radiator using this embodiment is much lower than that of a traditional radiator. Based on the lower inlet pressure, it can be proven that the radiator provided in this embodiment has higher cooling efficiency.

[0049] like Figure 9 As shown, the relationship between different numbers of baffles and heat dissipation effect and inlet pressure is illustrated, which provides guidance for the subsequent fabrication of corresponding radiators.

[0050] This invention achieves improvements in module packaging and heat sink design and fabrication processes through innovations such as the collaborative design of microchannel-chip arrangement, changes in the guiding structure of the shunt layer, and the overall module packaging method. This overcomes traditional power module heat dissipation problems, including low heat dissipation efficiency of traditional cooling structures, large junction temperature differences between chips, and poor heat sink structure flexibility.

[0051] The above examples illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A power module integrating three-dimensional stacked manifold microchannel cooling, comprising a copper-clad ceramic plate, and chips and heat sinks arranged on the upper and lower sides of the copper-clad ceramic plate, characterized in that, The radiator includes a microchannel layer with a microchannel structure arranged on the copper-clad ceramic plate, and a manifold layer covering the microchannel structure. The manifold layer includes a grid structure composed of multiple manifold walls and baffles. In the grid structure, two adjacent grids and the microchannel structure form a cooling channel for the coolant to flow vertically. The grid structure is constructed by setting multiple baffles between two adjacent manifold walls. The staggered arrangement angle of the manifold walls and microchannels is in the range of 30~90°. The baffles connect adjacent grid structures in series. The grid structure divides the microchannel structure below into different lengths, thereby realizing the adjustment of coolant flow rate at different positions. Based on the distribution of heat-generating parts of the chip, the grid structure of the manifold layer is adjusted: for areas of the chip where the local temperature rises rapidly, the number of grids is increased to improve the flow rate of the coolant.

2. A method for packaging a power module, characterized in that, For fabricating the power module with integrated three-dimensional stacked manifold microchannel cooling as described in claim 1, comprising: Step 1: Based on the size of the copper-clad ceramic substrate and the chip arrangement, prepare microchannel layers and manifold layers of corresponding sizes; Step 2: Polish the microchannel structure in the microchannel layer and the grid in the manifold layer; Step 3: Print nano-silver paste on the microchannel structure contact surface between the manifold layer and the microchannel layer using a silver film transfer process, and perform hot pressing treatment using a pressure silver sintering equipment to obtain a heat sink. Step 4: The heat sink and copper-clad ceramic plate are packaged sequentially using silver sintering process, and the copper-clad ceramic plate and chip are packaged together. At the same time, the input and output terminals of the chip are connected by soldering.

3. The packaging method for the power module according to claim 2, characterized in that, The structure of the microchannel layer and the horizontal deviation of the surface of the manifold layer are 1 to 20 micrometers.

4. The packaging method for the power module according to claim 2, characterized in that, In step 2, the polishing process includes physical polishing, rinsing to remove impurities and oxide layers.

5. The packaging method for a power module according to claim 2, characterized in that, In step 4, the welding methods include reflow soldering and ultrasonic soldering.

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