Novel three-dimensional packaging structure based on flexible substrate and chip heat dissipation method

Abstract

The invention discloses a novel three-dimensional packaging structure based on a flexible substrate and a chip heat dissipation method, particularly relates to the technical field of micro three-dimensional integrated circuit packaging structures, and solves the problems that in the prior art, a chip packaging structure is low in integration level and poor in heat dissipation performance, and the manufacturing process of a silicon through hole technology in advanced packaging is complex; in the prior art, a silicon chip needs to be drilled and filled with a conductive material, so that the production cost is increased, the drilling and filling process has extremely high requirements on precision and control, and secondly, signal interference is caused, and a series of signal distortion and crosstalk problems can be caused in the field of high-frequency signals due to the fact that a TSV is vertical; according to the technical scheme, a rigid-flexible combined packaging structure, a rigid metal stable three-dimensional packaging structure and a flexible substrate are adopted, and expensive technologies such as through silicon vias are not used; according to the three-dimensional packaging structure, essence of the rigid substrate and essence of the flexible substrate are respectively taken, dregs are removed, and the rigid substrate and the flexible substrate make up for each other.

Description

Technical Field

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

[0002] According to many IC industry data, with the continuous development of the integrated circuit industry, electronic devices are constantly shrinking along with Moore's Law, and the challenges of the Moore era are also coming. The reduction of transistor size has approached the physical limit, which makes it increasingly difficult to continue to follow Moore's Law. The three-dimensional packaging structure (3DPackaging Structure) has gradually become an important development trend. Modern electronic products have increasing performance requirements, especially in terms of data processing speed and computing power. Traditional two-dimensional packaging structures often have limitations in signal transmission and power consumption management between chips. Three-dimensional packaging achieves a shorter signal transmission path by stacking multiple chips together, thereby significantly improving data transmission speed and processing efficiency. In addition, the three-dimensional packaging structure can effectively reduce interference between circuits and improve the overall performance of the system. Therefore, optimizing the three-dimensional packaging structure can significantly improve the processing power and response speed of electronic devices, enabling them to meet the needs of high-performance applications.

[0003] Again, optimizing the three-dimensional packaging structure is of great significance to meeting the increasingly stringent market demands. With the advancement of science and technology, the market has higher and higher requirements for electronic products, including smaller size, higher performance and longer life. The optimization of the three-dimensional packaging structure can effectively meet these challenges, enabling electronic products to achieve higher performance in a smaller volume while improving product reliability and durability. By continuously optimizing the packaging structure, manufacturers can better adapt to market changes and meet consumer needs, thereby gaining an advantage in a 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 to improving the performance, reliability and production efficiency of electronic products.

[0004] The existing paper "Analysis and Protection Design of Electromagnetic Interference in Three-Dimensional Packages" (2017) focuses on the EMC problem of "interference within the package". Based on the transmission line theory, the equivalent circuit model of through silicon vias (TSVs) in three-dimensional packages is derived, and a lumped parameter model including resistance, inductance, capacitance and conductance is established. In addition, the multiple reflection and scattering problems of large-scale array TSVs are studied, and a field-circuit collaborative simulation method is proposed. This method is based on the expansion of the scattering matrix and cylindrical wave mode, and takes into account the multiple reflections and scattering of electromagnetic waves between TSV / TGV arrays, which can effectively analyze the electromagnetic characteristics of large-scale TSV / TGV arrays. It can be seen from the article that the cost and difficulty of manufacturing through silicon vias TSV are high, 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 conductive sheet are packaged inside the packaging body, a heat sink is arranged above the heat conductive sheet, and both the heat conductive sheet and the heat sink have an A surface and a relative B surface. The A surface of the heat conductive sheet is arranged on the back of the electronic component, and the B surface of the heat conductive sheet is flush with the top surface of the packaging body and exposed, and connected to the B surface of the heat sink. The A surface of the heat conductive sheet is uniformly sunken with multiple first grooves, and the first grooves reduce the stress of the heat conductive sheet on the electronic component. The A surface of the heat sink is uniformly sunken with multiple second grooves to enhance heat dissipation. The first groove is filled with packaging material. By arranging the heat conductive sheet between the electronic component and the heat sink, the heat of the electronic component is completely transferred to the heat sink. The second groove increases the heat dissipation area, and the heat dissipation effect is good. The A surface of the heat conductive sheet is sunken with multiple first grooves, 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 of a board-level fan-out flexible packaging substrate and its preparation method" discloses a packaging structure of a board-level fan-out flexible packaging substrate and its preparation method, providing a flexible substrate, and the flexible substrate is connected to a copper column; the plastic sealing layer and the dielectric layer are grooved to form a dividing groove between each chip, and a filling layer is made between the dielectric layer and the flexible substrate to complete the flexible packaging. The front-end process is completed by using board-level fan-out packaging technology for flexible packaging, and the plastic sealing board with a copper column structure and the flexible substrate are interconnected by using 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 that the heat dissipation performance of the flexible substrate is poor, and no optimization is made.

[0007] The existing patent "Top and bottom double heat sink packaging structure" provides a new type of top and bottom double heat sink packaging structure, which is to apply solder on a lead frame, attach and fix the semiconductor chip on the solder, and then apply solder on the surface above 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 on the top and bottom. The way to dissipate heat from the top of the package is increased, providing better heat dissipation characteristics for high-power semiconductor devices. However, this method does not take into account that the addition of heat sinks will greatly increase the volume of the package with increasing integration, which is contrary to the increase in integration.

[0008] In summary: the existing technology has the following disadvantages: 1. Most of the traditional heat dissipation structures are based on low-cost heat sinks, but they have not considered that while saving costs, the volume of the package is also increased, which is not conducive to increasing the degree of integration. 2. Under the premise of applying its shape variability, the heat dissipation performance of the existing advanced flexible substrate in the package is still relatively poor, and there are no clear measures to optimize it. 3. Some packaging structures are only suitable for two-dimensional packaging and are not suitable for three-dimensional packaging. 4. The manufacturing process of through silicon via technology in advanced packaging is complicated. It is necessary to drill holes on the silicon chip and fill it with conductive materials, which increases the production cost. As described in the paper, the manufacturing process takes many factors into consideration, so that the drilling and filling processes have extremely high requirements for precision and control. Any slight deviation may lead to interconnection failure, high cost and difficult manufacturing. 5. The second is signal interference. Since TSV is vertical, it will cause a series of signal distortion and crosstalk problems in the field of high-frequency signals. Summary of the invention

[0009] Therefore, the present invention solves the problems in the prior art that the chip packaging structure has low integration, poor heat dissipation performance, and is not suitable for three-dimensional packaging. The manufacturing process of silicon via technology in advanced packaging is complicated, and it is necessary to drill holes on the silicon chip and fill them with conductive materials, which increases the production cost. As described in the paper, the manufacturing process takes into account many factors, so that the drilling and filling processes have extremely high requirements for precision and control. Any slight deviation may lead to interconnection failure, high cost, and manufacturing difficulties. Secondly, there is signal interference. Since TSV is vertical, it will cause a series of signal distortion and crosstalk problems in the field of high-frequency signals. The present invention provides a new three-dimensional packaging structure based on a flexible substrate and a chip heat dissipation method, which provides a heat dissipation solution, has the advantages of ultra-high density integration and excellent heat dissipation, solves the problems of difficulty in making silicon vias in advanced packaging, high cost, poor heat dissipation of flexible substrates, and realization of 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 arranged inside the metal plate box, a signal distribution chip and other multifunctional chips are arranged on the flexible substrate; the signal distribution chip and the 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, and 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 three-dimensional packaging structure combining rigidity and flexibility; the poor heat dissipation performance of the flexible substrate is compensated.

[0011] Furthermore, the inner side wall of the heat dissipation and transmission multiplexing metal plate box is provided with a microchannel heat sink.

[0012] Furthermore, the microchannel heat sink extends into the bow-shaped flexible substrate, thereby better dissipating the heat of the chip on the flexible substrate.

[0013] Furthermore, a cooling liquid pool is provided on the top of the heat dissipation and transmission multiplexing metal plate box.

[0014] Furthermore, the signal distribution chip is arranged at the top of the bow-shaped flexible substrate, making it closer to the cooling liquid pool, and the heat dissipation effect in this area is better. A signal distribution chip is installed at the upper layer inside the package, and the signal distortion is monitored in real time through the package signal transmission path and prevented and corrected.

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

[0016] Furthermore, the signal distribution chip and the other multifunctional chips are connected to the flexible substrate through solder balls. The interconnection between chips is achieved by bonding the chip bumps and the heat dissipation transmission reuse metal plate bumps using metal pads to realize the interaction of the chips inside the package; both the chip bumps and the metal plate bumps can be solder balls.

[0017] Furthermore, a heat dissipation microfluidic channel is provided in the side wall of the heat dissipation transmission multiplexing metal plate box, which is connected with the internal channel of the microfluidic heat sink and the cooling liquid pool. A water pump is provided in the cooling liquid pool, and the water pump can drive the cooling liquid to flow; Figure 5 As shown, the heat dissipation microfluidic channel can be wavy in shape to further increase the heat dissipation area.

[0018] Furthermore, the heat dissipation microfluidic channel is staggered from the metal signal transmission line arranged 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 novel three-dimensional packaging structure based on the flexible substrate, characterized in that it comprises the following steps:

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

[0021] S2: By turning on the water pump, the coolant in the coolant pool flows to the heat dissipation microfluidic channel and the internal channel of the microfluidic heat sink, so that the heat dissipation transmission multiplexing metal plate box and the microfluidic heat sink cool the chip;

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

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

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

[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 packaging structure. The rigid metal stabilizes the three-dimensional packaging structure, and the flexible substrate avoids the use of expensive technologies such as through silicon vias to realize the three-dimensional packaging structure. The rigid and flexible substrates each take their essence and remove their dross to complement each other to realize the novel three-dimensional packaging structure of the present invention.

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

[0027] 4. The novel three-dimensional packaging structure based on a flexible substrate and a chip heat dissipation method provided by the present invention have a cooling liquid pool on the top of the packaging body, a water pump is installed inside the cooling liquid pool to drive the cooling liquid to circulate in a closed microchannel, and continuously deliver low-temperature cold water to the heat sink, almost accurately to all chips, to complete the heat dissipation of each chip.

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

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, 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 This is a schematic diagram of the structure of the heat dissipation and transmission multiplexing metal plate box of the present invention;

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

[0033] Figure 4 A top view of a water pump driving the cooling liquid pool of the present invention; Figure 5 Schematic diagram of the heat dissipation microfluidic channel of the present invention.

[0034] Description of reference numerals:

[0035] 1. Cooling liquid pool; 2. Signal distribution chip; 3. Flexible substrate; 4. Metal pad; 5. Microfluidic 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 DESCRIPTION

[0036] 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.

[0037] Embodiment 1:

[0038] 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 arranged in 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 through 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.

[0039] The heat dissipation transmission multiplexed metal plates are arranged in a rectangular cube outside the flexible substrate 3 to form a heat dissipation transmission multiplexed metal plate box 8, forming a rigid three-dimensional packaging structure. The rigid three-dimensional packaging structure realized by the heat dissipation transmission multiplexed metal plate box 8 and the flexible three-dimensional packaging structure realized by the "bow"-shaped flexible substrate 3 are combined to form a new three-dimensional packaging structure combining rigidity and flexibility; the poor heat dissipation performance of the flexible substrate 3 is compensated, and the heat dissipation capacity of the flexible substrate 3 is enhanced by using a rigid metal plate plus microchannel technology; at the same time, a rigid-flexible packaging structure is adopted, the rigid metal stabilizes the three-dimensional packaging structure, and the flexible substrate 3 avoids using expensive technologies such as silicon vias to realize the three-dimensional packaging structure. The rigid and flexible substrates each take their essence and remove their dross to complement each other; the three-dimensional packaging structure does not use a heat sink, thereby avoiding increasing the volume of the package body, and secondly avoids the production of silicon vias, with low cost, to achieve ultra-high density chip integration.

[0040] In this embodiment, a cooling liquid pool 1 is provided on the top of the heat dissipation transmission multiplexing metal plate box 8. The signal distribution chip 2 is provided at the top of the bow-shaped flexible substrate 3. The remaining multifunctional chips 6 are provided on the bow-shaped flexible substrate 3 from top to bottom according to the power level. The signal distribution chip 2 and the remaining multifunctional chips 6 are connected to the flexible substrate 3 through solder balls 7.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Embodiment 2:

[0046] 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:

[0047] S1: placing the chips on the bow-shaped flexible substrate 3 from top to bottom according to the power level;

[0048] 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;

[0049] S3: The cooling liquid pool 1 itself dissipates heat for the chip with the highest power that is closest to it.

[0050] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions 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: The invention 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 other multifunctional chips (6) are connected to the heat dissipation transmission multiplexing metal plate box (8) via a metal pad (4).

2. The novel three-dimensional packaging structure based on a flexible substrate according to claim 1, characterized in that: The inner side wall of the heat dissipation and transmission multiplexing metal plate box (8) is provided with a microchannel heat sink (5).

3. The novel three-dimensional packaging structure based on a flexible substrate according to claim 2, characterized in that: The microchannel heat sink (5) extends into the bow-shaped flexible substrate (3).

4. The novel three-dimensional packaging structure based on a flexible substrate according to claim 2, characterized in that: A cooling liquid pool (1) is arranged on the top of the heat dissipation and transmission multiplexing metal plate box (8).

5. 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).

6. 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.

7. 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).

8. The novel three-dimensional packaging structure based on a flexible substrate according to claim 4, characterized in that: 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).

9. The novel three-dimensional packaging structure based on a flexible substrate according to claim 8, 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).

10. 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 9, characterized in that: The steps include: S1: placing the chips from top to bottom on a bow-shaped flexible substrate (3) according to power levels; S2: by turning on the water pump (11), the coolant in the coolant pool (1) is allowed 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 cooling liquid pool (1) itself dissipates heat for the highest power chip closest to it.

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