A novel three-dimensional packaging structure based on a flexible substrate and a chip heat dissipation method

Abstract

The present invention discloses a novel three-dimensional packaging structure based on a flexible substrate and a chip heat dissipation method, specifically relating to the technical field of micro three-dimensional integrated circuit packaging structures, and solving the technical problems in the prior art that the chip packaging structure has low integration and poor heat dissipation performance, and the through-silicon via technology in advanced packaging has a complex manufacturing process, which requires drilling holes in a silicon chip and filling conductive materials, increasing production costs, so that the drilling and filling processes have extremely high requirements for precision and control. Secondly, there is signal interference. Since the TSV is vertical, it will cause a series of signal distortion and crosstalk problems in the high-frequency signal field. The technical solution is as follows: a rigid-flexible combined packaging structure is adopted, with a rigid metal to stabilize the three-dimensional packaging structure and a flexible substrate to avoid using costly technologies such as through-silicon vias. The three-dimensional packaging structure realized by the present invention takes the essence and discards the dross of the rigid and flexible substrates, and compensates for each other.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional integrated circuit packaging structures, and particularly to a novel three-dimensional packaging structure based on a flexible substrate and a chip heat dissipation method. Background Art

[0002] According to the information of many IC industries, with the continuous development of the integrated circuit industry, electronic devices have been continuously reduced according to Moore's law, and the challenges of the Moore era have followed. The reduction of transistor size has approached the physical limit, making it increasingly difficult to continue following Moore's law. The three-dimensional packaging structure (3D Packaging Structure) has gradually become an important development trend. Modern electronic products have increasingly high requirements for performance, especially in terms of data processing speed and computing power. Traditional two-dimensional packaging structures often have limitations in signal transmission between chips and power consumption management. By stacking multiple chips together, the three-dimensional packaging achieves a shorter signal transmission path, thus significantly improving the data transmission speed and processing efficiency. In addition, the three-dimensional packaging structure can effectively reduce the interference between circuits and improve the overall performance of the system. Therefore, optimizing the three-dimensional packaging structure can significantly enhance the processing ability and response speed of electronic devices, enabling them to meet the needs of high-performance applications.

[0003] Furthermore, optimizing the three-dimensional packaging structure is of great significance for meeting the increasingly stringent market demands. With the progress of technology, the market has higher and higher requirements for electronic products, including smaller size, higher performance, and longer lifespan, etc. The optimization of the three-dimensional packaging structure can effectively address these challenges, enabling electronic products to achieve higher performance within a smaller volume, while improving the reliability and durability of the products. By continuously optimizing the packaging structure, manufacturers can better adapt to market changes, meet the needs of consumers, and thus gain an advantage in the highly competitive market. Therefore, it is very necessary to optimize the three-dimensional structure of advanced packaging, and optimizing the three-dimensional packaging structure is crucial for improving the performance, reliability, and production efficiency of electronic products.

[0004] The existing paper "Analysis and Protection Design of Electromagnetic Interference in Three-Dimensional Packaging" (2017) addressed the EMC problem of "interference within the package". Based on the transmission line theory, an equivalent circuit model of the through-silicon via (TSV) in three-dimensional packaging was derived, and a lumped parameter model including resistance, inductance, capacitance, and conductance was established. In addition, the multiple reflection and scattering problems of large-scale array TSVs were studied, and a field-circuit co-simulation method was proposed. This method is based on the scattering matrix and cylindrical wave mode expansion, considering the multiple reflection and scattering of electromagnetic waves between TSV / TGV arrays, and can effectively analyze the electromagnetic characteristics of large-scale TSV / TGV arrays. It can be seen from the article that the cost of manufacturing through-silicon via TSVs is high and the difficulty is great, and the signal crosstalk problem is particularly critical.

[0005] The existing patent "A Chip Heat Dissipation Packaging Structure and Its Packaging Process" discloses a chip heat dissipation packaging structure and its packaging process, including a packaging body. An electronic component and a heat conducting sheet are encapsulated inside the packaging body. A heat sink is arranged above the heat conducting sheet. Both the heat conducting sheet and the heat sink have an A surface and an opposite B surface. The A surface of the heat conducting sheet is arranged on the back of the electronic component. The B surface of the heat conducting sheet is flush with the top surface of the packaging body and is exposed, and is connected to the B surface of the heat sink. A plurality of first grooves are evenly sunken in the A surface of the heat conducting sheet, and the first grooves reduce the stress of the heat conducting sheet on the electronic component. A plurality of second grooves are evenly sunken in the A surface of the heat sink to enhance heat dissipation. The first grooves are filled with packaging material. By arranging the heat conducting sheet between the electronic component and the heat sink, the heat of the electronic component is completely transferred to the heat sink. The second grooves increase the heat dissipation area and have good heat dissipation effect. A plurality of first grooves are sunken in the A surface of the heat conducting sheet, and the thermal stress extrusion is reduced. However, this method is only applicable to two-dimensional packaging and cannot achieve three-dimensional packaging.

[0006] The existing patent "A Packaging Structure and Its Preparation Method of a Fan-Out Flexible Packaging Substrate at Board Level" discloses a packaging structure and its preparation method of a fan-out flexible packaging substrate at board level, providing a flexible substrate, and connecting the flexible substrate with copper pillars; performing grooving treatment on the plastic encapsulation layer and the dielectric layer to form a dividing groove between each chip, and manufacturing a filling layer between the dielectric layer and the flexible substrate to complete the flexible packaging production. The front-end process of flexible packaging is completed by using the fan-out packaging technology at board level, and the interconnection between the plastic encapsulated board with a copper pillar structure and the flexible substrate is realized by using the flexible substrate interconnection technology. The packaging process is simple, the cost of flexible packaging is reduced, and the packaging efficiency and reliability are improved. However, this method does not realize the poor heat dissipation performance of the flexible substrate and does not make any optimization.

[0007] The existing patent "Top and Bottom Double Heat Sink Packaging Structure" provides a new top and bottom double heat sink packaging structure. In this structure, solder is dotted on a lead frame, a semiconductor chip is attached to the solder and fixed, and then solder is dotted on the upper surface of the semiconductor chip. A special metal bridge with heat dissipation function is placed on the semiconductor chip and encapsulated with plastic to form a packaging structure with the semiconductor chip in the middle and heat sinks at both its top and bottom. The way of heat dissipation from the top of the packaging is increased, providing better heat dissipation characteristics for high-power semiconductor devices. However, this method does not consider that adding heat sinks in a packaging body with increasing integration will greatly increase the volume, which goes against the rising integration.

[0008] In summary, the prior art has the following disadvantages: 1. Most of the traditional heat dissipation structures use low-cost heat sinks, but they do not consider that while saving costs, the volume of the package is also increased, which is not conducive to increasing the integration density. 2. The heat dissipation performance of existing advanced flexible substrates is still relatively poor under the premise of applying their shape variability, and there are no clear measures for optimization. 3. Some packaging structures are only suitable for two-dimensional packaging and not for three-dimensional packaging. 4. The manufacturing process of the through-silicon via technology in advanced packaging is complex and requires drilling holes in the silicon chip and filling them with conductive materials, which increases the production cost. As described in the paper, there are many considerations in the manufacturing process, so the drilling and filling processes have extremely high requirements for precision and control. Any slight deviation may lead to interconnection failures, high costs, and difficult manufacturing. 5. Secondly, there is signal interference. Since the TSV is vertical, it will cause a series of signal distortion and crosstalk problems in the high-frequency signal field. Summary of the Invention

[0009] Therefore, the present invention solves the technical problems in the prior art that the chip packaging structure has low integration density, poor heat dissipation performance, is not suitable for three-dimensional packaging, the manufacturing process of the through-silicon via technology in advanced packaging is complex and requires drilling holes in the silicon chip and filling them with conductive materials, which increases the production cost. As described in the paper, there are many considerations in the manufacturing process, so the drilling and filling processes have extremely high requirements for precision and control. Any slight deviation may lead to interconnection failures, high costs, and difficult manufacturing. Secondly, there is signal interference. Since the TSV is vertical, it will cause a series of signal distortion and crosstalk problems in the high-frequency signal field. The present invention provides a novel three-dimensional packaging structure based on a flexible substrate and a chip heat dissipation method, provides its heat dissipation solution, has the advantages of ultra-high density integration and excellent heat dissipation, and solves the problems of difficult production and high cost of through-silicon vias in advanced packaging, poor heat dissipation of flexible substrates, and realizing three-dimensional packaging.

[0010] The present invention provides a novel three-dimensional packaging structure based on a flexible substrate, including a heat dissipation transmission multiplexing metal plate box with a hollow bottom. A flexible substrate arranged in a bow shape is disposed inside the metal plate box, and a signal distribution chip and other multifunctional chips are arranged on the flexible substrate. The signal distribution chip and other multifunctional chips are connected to the heat dissipation transmission multiplexing metal plate box through metal pads. The heat dissipation transmission multiplexing metal plates are arranged in a rectangular cube outside the flexible substrate to form a heat dissipation transmission multiplexing metal plate box, forming a rigid three-dimensional packaging structure. The rigid three-dimensional packaging structure realized by the heat dissipation transmission multiplexing metal plate box and the flexible three-dimensional packaging structure realized by the "bow"-shaped flexible substrate are combined to form a novel rigid-flexible combined three-dimensional packaging structure, making up for the poor heat dissipation performance of the flexible substrate.

[0011] Furthermore, microchannel heat sinks are arranged on the inner side walls of the heat dissipation transmission multiplexing metal plate box.

[0012] Further, the microchannel heat sink extends into the bow-shaped flexible substrate, thereby better dissipating heat from the chips on the flexible substrate.

[0013] Further, a coolant pool is provided at the top of the heat dissipation transmission multiplexing metal plate box.

[0014] Further, the signal distribution chip is disposed at the topmost part of the bow-shaped flexible substrate, making it closer to the coolant pool, and the heat dissipation effect in this area is better. The signal distribution chip is installed at a high level inside the package, and the signal distortion situation is monitored in real time through the signal transmission path of the package and corrected.

[0015] Further, the remaining multifunctional chips are arranged on the bow-shaped flexible substrate from top to bottom according to their power levels.

[0016] Further, the signal distribution chip and the remaining multifunctional chips are connected to the flexible substrate through solder balls. The interconnection between the chips is bonded using metal pads through the chip bumps and the bumps of the heat dissipation transmission multiplexing metal plate, realizing the interaction of the chips inside the package; both the chip bumps and the metal plate bumps can be solder balls.

[0017] Further, heat dissipation microchannels are formed inside the side walls of the heat dissipation transmission multiplexing metal plate box, which are connected to the internal channels of the microchannel heat sink and the coolant pool. A water pump is provided in the coolant pool, and the water pump can drive the coolant to flow; as Figure 5 shown, the heat dissipation microchannels can be wavy, further increasing the heat dissipation area.

[0018] Further, the heat dissipation microchannels are staggered from the metal signal transmission lines provided on the outer surface of the heat dissipation transmission multiplexing metal plate box.

[0019] The present invention also provides a chip heat dissipation method based on the above-mentioned novel three-dimensional packaging structure based on a flexible substrate, which is characterized by including the following steps:

[0020] S1: Arrange the chips on the bow-shaped flexible substrate from top to bottom according to their power levels;

[0021] S2: By turning on the water pump, the coolant in the coolant pool flows into the heat dissipation microchannels and the internal channels of the microchannel heat sink, so that the heat dissipation transmission multiplexing metal plate box and the microchannel heat sink dissipate heat from the chips;

[0022] S3: The coolant pool itself dissipates heat from the chip with the highest power closest to it.

[0023] In the above technical solution, the technical effects and advantages provided by the present invention:

[0024] 1. The novel three-dimensional packaging structure and chip heat dissipation method based on a flexible substrate provided by the present invention make up for the poor heat dissipation performance of the flexible substrate. By using a rigid metal plate and microchannel technology, the heat dissipation ability of the flexible substrate is enhanced.

[0025] 2. The novel three-dimensional packaging structure and chip heat dissipation method based on a flexible substrate provided by the present invention adopt a rigid-flexible combined packaging structure. The rigid metal stabilizes the three-dimensional packaging structure, and the flexible substrate avoids using costly technologies such as through-silicon vias to achieve the three-dimensional packaging structure. The rigid and flexible substrates each take their advantages and make up for each other's disadvantages to realize the novel three-dimensional packaging structure of the present invention.

[0026] 3. The novel three-dimensional packaging structure and chip heat dissipation method based on a flexible substrate provided by the present invention is provided with a signal distribution chip inside the package. According to current data, the signal integrity problem is becoming more and more serious in the package. Therefore, a chip with an independent function is used to realize real-time monitoring of the signals inside the package to prevent signal distortion.

[0027] 4. The novel three-dimensional packaging structure and chip heat dissipation method based on a flexible substrate provided by the present invention is provided with a coolant pool on the top of the package. A water pump is installed inside the coolant pool to drive the circulation of the coolant in a closed microchannel, continuously delivering low-temperature cold water to the heat sink, almost precisely to all chips, to complete the heat dissipation of each chip.

[0028] 5. The novel three-dimensional packaging structure and chip heat dissipation method based on a flexible substrate provided by the present invention avoid increasing the volume of the package. Secondly, it avoids the fabrication of through-silicon vias, has a lower cost, and realizes ultra-high density chip integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0030] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 It is a schematic diagram of the structure of the heat dissipation transmission multiplexing metal plate box of the present invention;

[0032] Figure 3 It is a schematic diagram of the connection between the chips inside the package and the heat dissipation transmission multiplexing metal plate box of the present invention;

[0033] Figure 4 It is a top view of the water pump drive of the coolant pool of the present invention;

[0034] Figure 5 This is a schematic diagram of the heat dissipation microfluidic channel of the present invention.

[0035] Explanation of reference numerals:

[0036] 1. Coolant pool; 2. Signal distribution chip; 3. Flexible substrate; 4. Metal pad; 5. Microchannel heat sink; 6. Other multifunctional chips; 7. Solder ball; 8. Heat dissipation transmission multiplexing metal plate box; 9. Metal signal transmission line; 10. Heat dissipation microfluidic channel; 11. Water pump. Detailed implementation manners

[0037] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] Embodiment 1:

[0039] This embodiment provides a novel three-dimensional packaging structure based on a flexible substrate, including a heat dissipation transmission multiplexing metal plate box 8 with a hollow bottom. A flexible substrate 3 arranged in a bow shape is provided inside the metal plate box. A signal distribution chip 2 and other multifunctional chips 6 are provided on the flexible substrate 3. The signal distribution chip 2 and other multifunctional chips 6 are connected to the heat dissipation transmission multiplexing metal plate box 8 through metal pads 4. A microchannel heat sink 5 is provided on the inner side wall of the heat dissipation transmission multiplexing metal plate box 8. The microchannel heat sink 5 extends into the bow-shaped flexible substrate 3.

[0040] The heat dissipation transmission multiplexing metal plates are arranged in a rectangular cube outside the flexible substrate 3 to form a heat dissipation transmission multiplexing metal plate box 8, forming a rigid three-dimensional packaging structure. The rigid three-dimensional packaging structure realized by the heat dissipation transmission multiplexing metal plate box 8 and the flexible three-dimensional packaging structure realized by the "bow"-shaped flexible substrate 3 are combined to form a novel rigid-flexible combined three-dimensional packaging structure; it makes up for the poor heat dissipation performance of the flexible substrate 3. By using a rigid metal plate and microchannel technology, the heat dissipation ability of the flexible substrate 3 is enhanced; at the same time, a rigid-flexible combined packaging structure is adopted. The rigid metal stabilizes the three-dimensional packaging structure, and the flexible substrate 3 avoids using costly technologies such as through-silicon vias to realize the three-dimensional packaging structure. The rigid and flexible substrates each take their advantages and avoid their disadvantages and complement each other; the three-dimensional packaging structure does not use a heat sink, avoiding an increase in the volume of the package. Secondly, the production of through-silicon vias is avoided, and the cost is relatively low, realizing ultra-high density chip integration.

[0041] In this embodiment, a coolant pool 1 is provided on the top of the heat dissipation transmission multiplexing metal plate box 8. The signal distribution chip 2 is arranged at the top of the bow-shaped flexible substrate 3. The other multifunctional chips 6 are arranged on the bow-shaped flexible substrate 3 from top to bottom according to the power level. The signal distribution chip 2 and the other multifunctional chips 6 are connected to the flexible substrate 3 through solder balls 7.

[0042] The package body includes a signal distribution chip 2 and other multifunctional chips 6, which are bonded to the flexible substrate 3 through solder balls 7 to form a flexible package body. The chip and the external rigid package body are bonded through metal pads 4 at the bumps of the chip and the bumps of the heat dissipation transmission multiplexing metal plate box 8 to achieve chip signal transmission. The flexible package body is specially equipped with a signal distribution chip 2, which is used to prevent signal distortion, perform real-time detection and correction, and ensure the integrity of the signal inside the package body. The high-power chips are arranged at the top layer inside the package body. On the one hand, they can dissipate heat through the inside of the package body, and on the other hand, they can dissipate heat through the upper cooling liquid pool 1.

[0043] In this embodiment, a heat dissipation microfluidic channel 10 is opened in the side wall of the heat dissipation transmission multiplexing metal plate box 8, which is connected to the internal channel of the microfluidic heat sink 5 and the cooling liquid pool 1. A water pump 11 is arranged in the cooling liquid pool 1.

[0044] The microfluidic heat sink 5 is connected to the heat dissipation transmission metal plate box and arranged on the signal distribution chip 2. The other multifunctional chips 6 are cooled in real time through the microfluidic heat sink 5. A cooling liquid pool 1 is arranged on the upper part of the rigid package body, and a water pump 11 is built in to drive the cooling liquid to flow in the heat dissipation microfluidic channel 10 and the internal channel of the microfluidic heat sink 5 for heat dissipation.

[0045] In this embodiment, the heat dissipation microfluidic channel 10 is staggered with the metal signal transmission line 9 provided on the outer surface of the heat dissipation transmission multiplexing metal plate box 8. Thus, the signal transmission path and the heat dissipation microfluidic channel 10 are alternately arranged, which can dissipate heat for the chip and form a rigid package.

[0046] Embodiment 2:

[0047] This embodiment provides a chip heat dissipation method based on the novel three-dimensional packaging structure based on the flexible substrate, characterized in that it includes the following steps:

[0048] S1: placing the chips on the bow-shaped flexible substrate 3 from top to bottom according to the power level;

[0049] S2: Turn on the water pump 11 to allow the coolant in the coolant pool 1 to flow to the heat dissipation microfluidic channel 10 and the internal channel of the microfluidic heat sink 5, so that the heat dissipation transmission multiplexing metal plate box 8 and the microfluidic heat sink 5 can dissipate heat for the chip;

[0050] S3: The cooling liquid pool 1 itself dissipates heat for the chip with the highest power that is closest to it.

[0051] Only some exemplary embodiments of the present invention have been described by way of illustration. Without doubt, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A novel three-dimensional packaging structure based on a flexible substrate, characterized in that: It comprises a heat dissipation transmission multiplexing metal plate box (8) with a hollow bottom, wherein a flexible substrate (3) arranged in a bow shape is arranged inside the metal plate box, and a signal distribution chip (2) and other multifunctional chips (6) are arranged on the flexible substrate (3); the signal distribution chip (2) and the other multifunctional chips (6) are connected to the heat dissipation transmission multiplexing metal plate box (8) via a metal pad (4); The inner side wall of the heat dissipation transmission multiplexing metal plate box (8) is provided with a microchannel heat sink (5); The microchannel heat sink (5) extends into the bow-shaped flexible substrate (3); A cooling liquid pool (1) is arranged on the top of the heat dissipation transmission multiplexing metal plate box (8); A heat dissipation microfluidic channel (10) is provided in the side wall of the heat dissipation transmission multiplexing metal plate box (8), which is connected to the internal channel of the microfluidic heat sink (5) and the cooling liquid pool (1), and a water pump (11) is provided in the cooling liquid pool (1).

2. The novel three-dimensional packaging structure based on a flexible substrate according to claim 1, characterized in that: The signal distribution chip (2) is arranged on the top of the bow-shaped flexible substrate (3).

3. The novel three-dimensional packaging structure based on a flexible substrate according to claim 1, characterized in that: The remaining multifunctional chips (6) are arranged on the bow-shaped flexible substrate (3) in order from top to bottom according to power levels.

4. The novel three-dimensional packaging structure based on a flexible substrate according to claim 1, characterized in that: The signal distribution chip (2) and the remaining multifunctional chips (6) are connected to the flexible substrate (3) via solder balls (7).

5. The novel three-dimensional packaging structure based on a flexible substrate according to claim 1, characterized in that: The heat dissipation microfluidic channel (10) is staggered from the metal signal transmission line (9) arranged on the outer surface of the heat dissipation transmission multiplexing metal plate box (8).

6. A chip heat dissipation method based on the novel three-dimensional packaging structure based on a flexible substrate according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1: arranging chips from top to bottom on a bow-shaped flexible substrate (3) according to power levels; S2: turning on a water pump (11) to allow the coolant in the coolant pool (1) to flow to the heat dissipation microfluidic channel (10) and the internal channel of the microfluidic heat sink (5), so that the heat dissipation transmission multiplexing metal plate box (8) and the microfluidic heat sink (5) dissipate heat for the chip; S3: the coolant pool (1) itself dissipates heat for the chip with the highest power that is closest to it.

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