A board-level integrated heat dissipation structure for high-power SiP

Abstract

The present invention relates to the field of microelectronic integration technology, and specifically discloses a board-level integrated heat dissipation structure for high-power SiP, which is characterized by comprising a system motherboard, a high heat flux density SiP device mounted on the system motherboard, and a welding piece located between the system motherboard and the high heat flux density SiP device. The present invention effectively solves the technical problems of low board-level integrated heat dissipation efficiency, limited high-power applications, and contradiction with complex multi-layer wiring of the system. Compared with the prior art, it has a thinner thickness and meets the requirements of the thin and light of electronic devices.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic integration technology, and more particularly to a board-level integrated heat dissipation structure of a high-power SiP. Background Art

[0002] SiP (System in Packaging) integrates multiple different chips into a single package to form an independent packaged device with certain system-level or subsystem-level functions. Assembling SiP and other electronic components together on PCB (Printed Circuit Boards) forms a more complex board-level system.

[0003] However, when the above-mentioned board-level system is applied to high-power SiP, especially when the high-power SiP adopts high-density array integration, the total heat dissipation power of the board-level system may be as high as kilowatts. If there is no good heat dissipation, the high-power chip will have a reduced reliability or even burn out due to excessive junction temperature. Therefore, the heat dissipation technology used in the board-level system is very critical.

[0004] For example, Chinese patent CN108987942B discloses a high-power SiP board-level integrated heat dissipation structure surface-mounted flat active phased array antenna system architecture, in which the T / R component that mainly generates heat is directly fixed to the metal cold plate of the heat sink by screws, but the connection between the T / R component and the heat dissipation structure has a large thermal resistance, which becomes a bottleneck for further improving the power of the RF array. The heat dissipation structure is a metal part with a large volume and weight, which obviously affects the thinness of the system; Chinese patent CN111180899B discloses a high-power SiP board-level integrated heat dissipation structure based on a microsystem thin and light high-density integrated antenna array surface architecture, in which the four-channel chip-based active T / R component uses a high thermal conductivity HTCC (High Temperature Co-fired Ceramic) as the packaging substrate, and the chip heat is conducted to the upper metal cover plate through the HTCC circuit substrate and finally to the heat dissipation fins. In this solution, the heat dissipation path of the chip is long, and the thermal resistance is difficult to reduce, which cannot meet the application requirements of high heat flux density heat dissipation in high-power RF arrays.

[0005] The PCB heat dissipation components or structures disclosed in Chinese patents CN113709968A, CN103338613B, etc. use a heat-conducting structure that runs through the thickness of the PCB to conduct the heat generated by the device to the back, thereby enhancing the heat dissipation capacity. The through-heat-conducting structure used in this type of structure will seriously affect the effective wiring area of ​​the PCB, and especially in the case of dense array installation of high-power SiP, most of the area of ​​the PCB motherboard is occupied by the through-heat-conducting structure, and the remaining available area cannot meet the wiring requirements of power signal transmission, power supply network, control signal routing, etc. Therefore, this type of heat dissipation structure cannot meet the needs of high-density array integration of high-power SiP.

[0006] In summary, for the heat dissipation problems existing in board-level systems, the current heat dissipation integrated structure has problems such as large size of heat dissipation components, large thermal resistance of heat dissipation paths, and unsuitability for high-power SiP high-density array integration, which limits the application of board-level system integration technology in high-power scenarios. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a board-level integrated heat dissipation structure for a high-power SiP; it effectively solves the technical problems of low board-level integrated heat dissipation efficiency, limited high-power applications, and conflicts with complex multi-layer wiring of the system. Compared with the existing technology, it is thinner and meets the demand for lightweight electronic equipment.

[0008] The solution adopted by the present invention to solve the technical problem is:

[0009] A high-power SiP board-level integrated heat dissipation structure comprises a system motherboard, a high heat flux density SiP device mounted on the system motherboard, and a welding piece located between the system motherboard and the high heat flux density SiP device.

[0010] The welding parts in the present invention serve as electrical interconnection interfaces to realize the interconnection between the system motherboard and the high heat flux density SiP device. On the other hand, as heat conduction paths, they can effectively shorten the length of the heat conduction paths, reduce thermal resistance, and meet the requirements of lightness and thinness without increasing the overall thickness.

[0011] In some possible implementations, the system motherboard can effectively realize functions such as signal transmission, control signal routing, and power supply;

[0012] The system motherboard includes an upper wiring layer located at the bottom of a high heat flux density SiP device and connected thereto, a metal core located at the bottom of the upper wiring layer and passing through the upper wiring layer and welded to the high heat flux density SiP device, and a lower wiring layer located at the bottom of the metal core; there is a gap between the upper wiring layers; and the metal core is made of copper or aluminum.

[0013] In some possible implementations, in order to solve the contradiction that when improving heat exchange efficiency and reducing coolant flow resistance, an overly thick metal core will make system motherboard processing difficult and increase the thickness and weight of board-level integration;

[0014] The metal core comprises a core body located between an upper wiring layer and a lower wiring layer, and a boss mounted on the core body and integrally formed with the core body. The boss passes through the upper wiring layer and is connected to a high heat flux density SiP device.

[0015] In some possible implementations, in order to improve heat exchange efficiency, reduce coolant flow resistance, reduce thermal resistance, and not increase the total thickness of the metal core at all;

[0016] A liquid cooling channel is arranged in the boss.

[0017] In some possible implementations, the liquid cooling channel is a plurality of channels which are arranged in parallel, and the axes thereof are perpendicular to the upper and lower surfaces of the metal core, and the aspect ratio thereof is 1:1 to 5:1.

[0018] In some possible implementations, in order to effectively realize the electrical and thermal integration of low thermal resistance between the system motherboard and the high heat flux density SiP device;

[0019] The welding part includes a welding component 1 which is arranged in the gap and connected to the upper wiring layer and the bottom of the high heat flux density SiP device respectively, and a thermal conductive pad which is arranged at the bottom of the high heat flux density SiP device and welded to the boss; the thermal conductive pad is located directly above the boss.

[0020] In some possible implementations, there is a height difference between an upper surface of the boss and an upper surface of an upper wiring layer, and the height difference is 0.3-1.0 mm.

[0021] In some possible implementations, the high heat flux density SiP device includes a packaging substrate connected to the high heat flux density SiP device and a power chip mounted on the packaging substrate.

[0022] In some possible implementations, in order to effectively shorten the heat conduction distance, the thermal resistance of the heat dissipation path is reduced;

[0023] The packaging substrate is a ceramic packaging substrate, preferably an aluminum nitride HTCC substrate, and a blind groove for mounting a power chip is provided on the packaging substrate. The power chip is mounted in the blind groove through a low thermal resistance bonding material.

[0024] In some possible implementations, in order to effectively reduce the thermal resistance on the heat conduction path, the high heat flux density SiP device and the metal core are welded using a vacuum-assisted SMT welding process.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention realizes a high aspect ratio liquid cooling channel with efficient heat exchange in an extremely thin metal core by providing a boss structure, thereby effectively improving the heat dissipation capacity;

[0027] The present invention has no significant impact on the multi-layer wiring of the package substrate and the multi-layer wiring of the system motherboard, and can simultaneously meet the complex wiring requirements of high-power signal transmission, power supply network, control signal routing, etc., and can especially meet the application requirements of high-power SiP high-density array board-level integration;

[0028] The present invention further reduces the thickness of the board-level integration by using the system motherboard with built-in liquid cooling channels and the components installed on the motherboard, without the need for additional structural parts such as a heat sink and a cold plate, making the advantages of the board-level integration more prominent.

[0029] The present invention connects the heat-conducting pad to the boss in the metal core and utilizes the liquid cooling channel in the boss to improve the heat exchange efficiency by 30%, reduce the cooling liquid flow resistance by 50%, and does not increase the total thickness of the metal core at all. In addition, the boss further shortens the distance between the liquid cooling channel and the chip, effectively reducing the thermal resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the connection relationship of the present invention;

[0031] Figure 2 A schematic diagram showing the positional relationship between the thermal pad, welding assembly 1, and packaging substrate in the present invention;

[0032] Among them: 1. High heat flux density SiP device; 101. Power chip; 102. Package substrate; 104. Thermal pad; 2. System motherboard; 201. Upper wiring layer; 202. Metal core; 203. Lower wiring layer; 204. Liquid cooling channel; 205. Boss; 301. Welding component one. DETAILED DESCRIPTION

[0033] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. The "first", "second" and similar words mentioned in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, "one" or "one" and other similar words do not indicate a quantity restriction, but indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" refers to two or more. For example, multiple positioning columns refer to two or more positioning columns. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] The present invention is described in detail below.

[0035] like Figure 1-Figure 2 As shown:

[0036] A high-power SiP board-level integrated heat dissipation structure comprises a system motherboard 2, a high heat flux density SiP device 1 mounted on the system motherboard 2, and a welding piece located between the system motherboard 2 and the high heat flux density SiP device 1.

[0037] The welding part in the present invention serves as an electrical interconnection interface on the one hand to realize the interconnection between the system motherboard 2 and the high heat flux density SiP device 1, and on the other hand as a heat conduction path, it can also effectively shorten the length of the heat conduction path, reduce thermal resistance, and meet the demand for lightness and thinness without increasing the overall thickness.

[0038] In some possible implementations, the system motherboard 2 can effectively realize functions such as signal transmission, control signal routing, and power supply;

[0039] The system motherboard 2 includes an upper wiring layer 201 located at the bottom of the high heat flux density SiP device 1 and connected thereto, a metal core 202 located at the bottom of the upper wiring layer 201 and passing through the upper wiring layer 201 and welded to the high heat flux density SiP device 1, and a lower wiring layer 203 located at the bottom of the metal core 202; there is a gap between the upper wiring layer 201; the metal core 202 is made of copper or aluminum.

[0040] Preferably, the metal core 202 is made of copper or aluminum, which has the advantages of high thermal conductivity, mature flow channel processing technology, and compatibility with the system motherboard 2 processing technology.

[0041] Preferably, the thickness of the metal core 202 is 0.8-2.0 mm, which has little impact on the overall thickness of the integration.

[0042] The upper wiring layer 201 and the lower wiring layer 203 jointly realize functions such as power signal transmission, control signal routing, power supply, etc. The upper wiring layer 201, the lower wiring layer 203, and the metal core 202 are pressed and interconnected by metallization using PCB processing technology.

[0043] In some possible implementations, in order to solve the contradiction that when improving heat exchange efficiency and reducing coolant flow resistance, an overly thick metal core 202 will cause difficulty in processing the system motherboard 2 and increase the integrated thickness and weight of the array;

[0044] The metal core 202 includes a core body located between an upper wiring layer 201 and a lower wiring layer 203 , and a boss 205 mounted on the core body and integrally formed with the core body. The boss 205 passes through the upper wiring layer 201 and is connected to the high heat flux density SiP device 1 .

[0045] In some possible implementations, in order to improve heat exchange efficiency, reduce coolant flow resistance, reduce thermal resistance, and not increase the total thickness of the metal core 202 at all;

[0046] A liquid cooling channel is provided in the boss 205 .

[0047] In some possible implementations, the liquid cooling channel is a plurality of channels which are arranged in parallel, and the axes thereof are perpendicular to the upper and lower surfaces of the metal core, and the aspect ratio thereof is 1:1 to 5:1.

[0048] Further, such as Figure 1 As shown, the liquid cooling channel 204 is vertically arranged, perpendicular to the upper surface and the lower surface of the metal core 202, and there are multiple channels; Figure 1 As shown, the length is H, the width is B, and the typical H:B=3:1.

[0049] Preferably, the boss 205 penetrates the upper wiring layer 201 and is 0.3-1.0 mm higher than the upper wiring layer 201, typically 0.4 mm. By arranging a liquid cooling channel in the boss 205 and extending it into the core body, the heat exchange efficiency can be improved by 30%, the cooling liquid flow resistance can be reduced by 50%, and the total thickness of the metal core 202 is not increased at all. The arrangement of the boss 205 further shortens the distance between the liquid cooling channel and the power chip 101, effectively reducing the thermal resistance.

[0050] In some possible implementations, in order to effectively realize the electrical and thermal integration of low thermal resistance between the system motherboard 2 and the high heat flux density SiP device 1;

[0051] The welding part includes a welding component 301 arranged in the gap and connected to the upper wiring layer 201 and the bottom of the high heat flux density SiP device 1 respectively, and a thermal conductive pad 103 arranged at the bottom of the high heat flux density SiP device 1 and welded to the boss 205; the thermal conductive pad 103 is located directly above the boss 205.

[0052] Preferably, at least one group of thermal pads 103 is used as a heat dissipation conduction interface, and the thermal pads 103 are located directly opposite to the bottom of the power chip 101, which effectively shortens the length of the heat conduction path and reduces thermal resistance.

[0053] The welding components 1 301 are multiple groups, located outside the boss 205, and are evenly arranged in the gap; the welding components 1 301 can be BGA solder balls or CGA solder columns;

[0054] Preferably, the height difference between the BGA solder ball or CGA solder column and the boss 205 is within 0.1 mm, so that the BGA solder ball or CGA solder column and the thermal pad 103 can be well soldered to the system motherboard 2 at the same time.

[0055] There are multiple groups of BGA solder balls or CGA solder columns, which are used as electrical interconnection interfaces between the high heat flux density SiP device 1 and the system motherboard 2 through the BGA solder balls in a ball grid array or the CGA solder columns in a column grid array.

[0056] In the prior art, the thicker the metal core 202 is, the denser and larger the flow channels can be arranged, which improves the heat exchange efficiency and reduces the flow resistance of the coolant. However, an overly thick metal core 202 will make the system motherboard 2 difficult to process and increase the integrated thickness and weight of the array.

[0057] In the present invention, in order to solve the above problems, the thermal pad 103 installed at the bottom of the high heat flux density SiP device 1 corresponds to the position of the boss 205, and the boss 205 penetrates the upper multi-layer wiring of the system motherboard 2 and is 0.4 mm higher than the surface of the motherboard; the boss 205 is used to layout the liquid cooling channel with a depth to width ratio of 1:1 to 5:1 in the metal core 202. When the typical depth to width ratio is 3:1, the heat exchange efficiency can be improved by 30%, and the cooling liquid flow resistance can be reduced by 50%, and the total thickness of the metal core 202 is not increased at all. The boss 205 further shortens the distance between the liquid cooling channel and the chip, effectively reducing the thermal resistance.

[0058] In some possible implementations, the high heat flux density SiP device 1 includes a packaging substrate 102 connected to the high heat flux density SiP device 1 and a power chip 101 mounted on the packaging substrate 102 .

[0059] In some possible implementations, in order to effectively shorten the heat conduction distance, the thermal resistance of the heat dissipation path is reduced;

[0060] The packaging substrate 102 is a ceramic packaging substrate, preferably an aluminum nitride HTCC substrate, and a blind groove for mounting the power chip 101 is provided on the packaging substrate 102. The power chip 101 is embedded in the blind groove through a low thermal resistance bonding material.

[0061] The package substrate 102 is typically a multi-layer aluminum nitride HTCC circuit substrate, so that the thermal conductivity of the substrate can reach above 170 W / mK.

[0062] The low thermal resistance bonding material may be a gold-tin eutectic solder, nano-silver, nano-copper or other bonding materials;

[0063] The heat generated by the power chip 101 is conducted to the outside of the package through the low thermal resistance bonding material and the package substrate 102; the heat conduction distance is shortened by the blind groove, and the thermal resistance of the heat dissipation path is reduced.

[0064] The electrical signals of the package substrate 102 are led to the outer surface of the package substrate 102 through the conductive vias and multi-layer wirings in the package substrate 102 .

[0065] In some possible implementations, in order to effectively reduce the thermal resistance on the heat conduction path, the high heat flux density SiP device 1 and the metal core 202 are welded using a vacuum-assisted SMT welding process.

[0066] The vacuum-assisted SMT welding process is used to reduce the voids in the welding material when the thermal pad 103 and the boss 205 are welded, so that the void ratio is less than 5%, thereby effectively reducing the thermal resistance on the heat conduction path.

[0067] Through simulation and actual measurement, it is verified that the heat dissipation integrated structure of the present embodiment can reduce the thermal power consumption of the power chip 101 by more than 400W / cm 2 When the power chip 101 is connected to the board, the junction temperature of the power chip 101 is still within the safe range, meeting the requirements for long-term reliable operation of the high-power chip 101. In addition, the entire board-level integrated system does not contain additional heat sinks or cold plates, and the total thickness is less than 10 mm, which has obvious advantages of being lightweight and thin.

[0068] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A board-level integrated heat dissipation structure for high-power SiP, It is characterized in that It includes a system motherboard, a high heat flux density SiP device installed on the system motherboard, and a welding part located between the system motherboard and the high heat flux density SiP device; the system motherboard includes an upper wiring layer located at the bottom of the high heat flux density SiP device and connected thereto, a metal core located at the bottom of the upper wiring layer and passing through the upper wiring layer and welded to the high heat flux density SiP device, and a lower wiring layer located at the bottom of the metal core; there is a gap between the upper wiring layers; the metal core includes a core body located between the upper wiring layer and the lower wiring layer, a boss installed on the core body and integrally formed with the core body, the boss passes through the upper wiring layer and is connected to the high heat flux density SiP device; a liquid cooling channel is arranged in the boss; the welding part includes a welding component 1 arranged in the gap and connected to the upper wiring layer and the bottom of the high heat flux density SiP device respectively, and a heat conductive pad arranged at the bottom of the high heat flux density SiP device and welded to the boss; the heat conductive pad is located directly above the boss; the welding part serves as an electrical interconnection interface between the high heat flux density SiP device and the system motherboard; There is a height difference between the upper surface of the boss and the upper surface of the upper wiring layer, and the height difference is 0.3~1.0mm; the first welding component is a BGA solder ball or a CGA solder column; the height difference between the BGA solder ball or the CGA solder column and the height of the boss is within 0.1mm.

2. A board-level integrated heat dissipation structure of a high-power SiP according to claim 1, It is characterized in that The liquid cooling channels are multiple and arranged in parallel, and their axes are perpendicular to the upper and lower surfaces of the metal core, and their length-to-width ratio is 1:1-5:

1.

3. The board-level integrated heat dissipation structure of a high-power SiP according to claim 1, It is characterized in that The metal core is made of copper or aluminum.

4. The board-level integrated heat dissipation structure of a high-power SiP according to claim 1, It is characterized in that The high heat flux density SiP device comprises a packaging substrate connected to the high heat flux density SiP device and a power chip mounted on the packaging substrate.

5. A high-power SiP board-level integrated heat dissipation structure according to claim 4, It is characterized in that The packaging substrate is a ceramic packaging substrate and is provided with a blind groove for mounting a power chip. The power chip is mounted in the blind groove through a low thermal resistance bonding material.

6. The board-level integrated heat dissipation structure of a high-power SiP according to claim 1, It is characterized in that The high heat flux density SiP device and the metal core are welded using a vacuum-assisted SMT welding process.

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