Miniature capillary heat conductor, miniature high-heat-density equipment and heat conductor installation method

Abstract

The invention belongs to the technical field of optical communication, and relates to a miniature capillary heat conductor, miniature high-heat-density equipment and a heat conductor installation method, and the heat conductor comprises a shell and a heat conduction module packaged in the shell; the heat conduction module comprises a first heat conduction block, a second heat conduction block, a third heat conduction block and a fourth heat conduction block, each of the first heat conduction block, the second heat conduction block, the third heat conduction block and the fourth heat conduction block comprises a plurality of layers of microcirculation units, and each microcirculation unit is filled with a phase change working medium; the microcirculation unit comprises a heat absorption area, an evaporation area and a heat dissipation area which are communicated in sequence, the heat absorption area is used for making contact with the back face of the chip to conduct heat, the evaporation area extends downwards and outwards from the heat absorption area to the heat dissipation area, the heat dissipation area is used for dissipating heat to the back face of the PCB, the area of the heat dissipation area is larger than that of the heat absorption area, and the heat dissipation area is located on the outer side of the heat absorption area; the beneficial effect of the invention is that the technical problem that the heat conduction efficiency is not ideal because the existing optical module conducts heat through the PCB via hole on the back of the chip is solved.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a micro capillary heat conductor, a micro high heat density device and a heat conductor installation method. Background Art

[0002] During the heat dissipation process of an optical module, heat is transferred from the module to the system primarily through conduction, convection, and radiation. Optical modules are small and micro devices, so forced convection (such as a fan) is not an option. Instead, they rely on conduction to transfer heat to the housing, where it is then dissipated through convection.

[0003] In optical modules, TIA (transimpedance amplifier) ​​chips face unique heat dissipation challenges: their front surfaces require gold wires to connect to optical components, preventing direct heat dissipation through the outer casing. Therefore, heat dissipation relies primarily on the PCB's thermal conductivity design on the backside of the chip. Currently, mainstream solutions include hollow vias, solid vias, and copper-filled vias. Hollow vias involve drilling holes in the PCB and then plating the walls with copper, leaving the center hollow. This layer of copper conducts heat. Solid vias completely fill the inside of the via with copper, forming a solid copper column and providing a continuous vertical heat conduction path. Copper-filled vias involve filling the via with a highly thermally conductive material (such as copper paste, silver paste, or a resin mixture) rather than pure copper. However, the thermal efficiency of these solutions is suboptimal.

[0004] Therefore, it is necessary to design a thermal conductive device suitable for micro devices to efficiently dissipate heat from the heat-generating chip. Summary of the Invention

[0005] (1) Technical issues to be resolved In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a micro capillary heat conductor, a micro high heat density device, and a heat conductor installation method, which solves the technical problem that the existing optical module conducts heat through the PCB vias on the back of the chip, resulting in less than ideal thermal conductivity efficiency.

[0006] (2) Technical solution In order to achieve the above objectives, the main technical solutions adopted by the present invention include: In a first aspect, an embodiment of the present invention provides a micro-capillary heat conductor that can be embedded in a PCB circuit board and can conduct heat generated by chip operation from the front side of the PCB circuit board to the back side of the PCB circuit board. The heat conductor includes a housing and a heat conduction module, wherein the heat conduction module is encapsulated in the housing; the heat conduction module includes a first heat conduction block, a second heat conduction block, a third heat conduction block, and a fourth heat conduction block that abut to form a cross-square structure. The first heat conduction block, the second heat conduction block, the third heat conduction block, and the fourth heat conduction block each include several layers of transversely stacked microcirculation units, and each microcirculation unit is infused with a phase change working medium; the microcirculation unit includes a heat absorption zone, an evaporation zone, and a heat dissipation zone that are connected in sequence. The heat absorption zone is used to contact the back side of the chip for heat conduction. The evaporation zone extends downward and outward from the heat absorption zone to the heat dissipation zone. The heat dissipation zone is used to dissipate heat to the back side of the PCB circuit board. The area of ​​the heat dissipation zone is larger than that of the heat absorption zone and is located outside the heat absorption zone.

[0007] Optionally, the heat absorption areas of each microcirculation unit are aggregated and raised in the middle area of ​​the top surface of the heat conduction module to form a rectangular heat absorption surface, and the heat dissipation areas of each microcirculation unit are aggregated on the bottom surface of the heat conduction module to form a heat dissipation surface.

[0008] Optionally, the microcirculation unit includes a plurality of capillaries arranged side by side and connected together, the phase change working medium is perfused in the capillaries, the capillaries include a heat absorption branch, an evaporation branch and a heat dissipation branch, all the heat absorption branches in the microcirculation unit are aggregated into a heat absorption area, all the evaporation branches in the microcirculation unit form an evaporation area, and all the heat dissipation branches in the microcirculation unit are aggregated into a heat dissipation area; Each capillary tube is provided with two evaporation branches, one end of the two evaporation branches is connected through a heat absorption branch, and the other end of the two evaporation branches is connected through a heat dissipation branch to form a closed loop. The evaporation branches are stepped structures so that the evaporation areas of adjacent microcirculation units are stacked together.

[0009] Optionally, a gap is reserved between the two evaporation branches of the same capillary tube so that they do not contact each other.

[0010] Optionally, the microcirculation unit is further provided with a connecting pipe for perfusing the phase change working medium, the connecting pipe is connected to each capillary tube, one side of the connecting pipe is connected to the evaporation branch of each capillary tube, and the other side is connected to the heat dissipation branch of each capillary tube.

[0011] Optionally, the microcirculation unit at the junction of the first heat conducting block and the second heat conducting block is provided with two connecting pipes.

[0012] Optionally, the housing is a rectangular parallelepiped, or a cross-shaped square structure adapted to the heat conduction module.

[0013] In a second aspect, an embodiment of the present invention provides a miniature high heat density device, comprising a device housing, a PCB circuit board, a chip, and the aforementioned miniature capillary heat conductor; the PCB circuit board is placed in the device housing, and the bottom surface of the PCB circuit board is in contact with the device housing. The PCB circuit board is provided with a slot, and the heat conductor is embedded in the slot. The chip is arranged on the top surface of the heat conductor and is welded to the PCB circuit board. The heat conductor contacts the chip for heat conduction, so as to transfer the heat of the chip to the device housing.

[0014] Optionally, a heat conducting plate is provided between the PCB circuit board and the device housing.

[0015] In a third aspect, an embodiment of the present invention provides a heat spreader installation method for embedding the aforementioned heat spreader on a PCB circuit board, comprising the following steps: S1. Mill a slot for placing the heat conductor on the inner core board or prepreg of the PCB circuit board; S2. browning or blackening the shell of the heat conductor to form a rough oxide layer on the outer surface of the shell of the heat conductor; S3. Align and stack the sheets including the inner core board with slots cut in, the prepreg, and the copper foil layer according to the preset stacking structure, and place the browned or blackened heat conductor into the pre-milled slots; S4. The sheet material is fed into a vacuum laminator and laminated under high temperature and high pressure conditions to obtain an integrated finished structure of the PCB circuit board and the heat conductor.

[0016] (3) Beneficial effects The beneficial effects of the present invention are: 1. The micro-capillary heat conductor, micro-high heat density device, and heat conductor installation method of the present invention utilize a cross-shaped block structure composed of a first heat-conducting block, a second heat-conducting block, a third heat-conducting block, and a fourth heat-conducting block. Each heat-conducting block is stacked with multiple microcirculation units. The heat generated by the chip can be conducted downward layer by layer and in four directions through the microcirculation units of each heat-conducting block. This provides a large contact area between the fluid and the pipe wall per unit volume, allowing heat to be transferred more quickly from the heat source to the phase change medium flowing through the channel. This results in a larger heat conduction area, higher heat conduction efficiency, and stronger heat conduction performance. Compared to the prior art, this solves the technical problem of existing optical modules conducting heat through PCB vias on the back of the chip, which suffers from suboptimal heat conduction efficiency.

[0017] 2. Due to the high thermal conductivity of the heat conductor, it can handle a higher heat flux density per unit area, thus reducing the volume of the heat conductor. It is suitable for products with small size, high integration, concentrated heat generation and high power, such as optical modules, radar systems, CPUs or GPUs and other computing chips. In an extremely limited space, it can quickly and evenly transfer the highly concentrated huge heat generated by electronic equipment or systems with extremely high efficiency (relative to traditional heat dissipation methods), ensuring stable, reliable and high-performance operation of the equipment within a safe temperature range, while meeting the needs of miniaturization, lightweight and low noise.

[0018] 3. The microcirculation unit is printed using 3D printing technology and includes multiple capillaries arranged side by side and connected together. The capillaries are connected and aggregated through connecting pipes to form a capillary heat conduction structure. The capillary heat conduction structure is closely arranged under or around the heat source. When the phase change working fluid flows through these channels, it can take away heat more directly and evenly, which helps to significantly reduce the temperature gradient on the surface of the heat source and avoid the occurrence of "hot spots", thereby improving the reliability, stability and performance of the equipment.

[0019] 4. The 3D-printed thermal module consists of multiple thermal blocks, each stacked with multiple microcirculation units. Each microcirculation unit is equipped with multiple capillaries. This allows for the integration of numerous heat dissipation channels within a compact space, achieving an extremely high heat dissipation density (heat dissipation capacity per unit volume). This makes the overall device design more compact and lightweight, making it particularly suitable for space-constrained applications such as laptops, smartphones, drones, and satellites.

[0020] 5. Due to the small size of the heat conductor, it can be directly embedded in any position of the PCB circuit board. The installation position is flexible and the area occupied is smaller, leaving more space for the PCB circuit board layout, reducing the design difficulty of the PCB circuit board.

[0021] 6. The microcirculation unit is equipped with multiple capillaries, each connected by a connecting tube. Each capillary has two evaporation branches. The phase-change working fluid is stored in the heat-absorbing branch and absorbs heat there. After absorbing heat, the phase-change working fluid evaporates and moves along the two evaporation branches to the heat-dissipating branch. The vaporized phase-change working fluid is cooled and liquefied in the heat-dissipating branch. The liquefied phase-change working fluid then flows back along the two evaporation branches to the heat-absorbing branch. This improves the working stability of the heat conductor, and the blockage of one branch will not affect the heat conduction of the heat conductor.

[0022] 7. The evaporation area of ​​the microcirculation unit is set as a step-like structure, which can not only allow two adjacent microcirculation units to be stacked together, but also increase the length of the heat conduction path, increase the heat conduction area, and achieve better heat conduction and heat dissipation effects.

[0023] 8. Each capillary of the microcirculation unit is uniformly perfused with phase change working fluid through a connecting pipe, which makes the operation more convenient.

[0024] 9. The heat conductor is directly embedded in the PCB circuit board, which can avoid the risk of product defects caused by complex punching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is one of the three-dimensional schematic diagrams of the heat conductor of Example 1 of the micro capillary heat conductor, micro high heat density device, and heat conductor installation method of the present invention; Figure 2 This is a second perspective schematic diagram of the heat conductor (the housing is not shown) of Example 1 of the micro capillary heat conductor, micro high heat density device, and heat conductor installation method of the present invention; Figure 3 This is the third three-dimensional schematic diagram of the heat conductor (the housing is not shown) of Example 1 of the micro capillary heat conductor, micro high heat density device, and heat conductor installation method of the present invention; Figure 4 Schematic front view of the heat conductor of Example 1 of the micro capillary heat conductor, micro high heat density device and heat conductor installation method of the present invention; Figure 5 Schematic bottom view of the heat conductor of Example 1 of the micro capillary heat conductor, micro high heat density device and heat conductor installation method of the present invention; Figure 6 Schematic cross-sectional view of the first heat conducting block and the second heat conducting block of the heat conductor of Example 1 of the micro capillary heat conductor, micro high heat density device and heat conductor installation method of the present invention; Figure 7 Schematic cross-sectional view of the fourth heat conducting block of the heat conductor of Example 1 of the micro capillary heat conductor, micro high heat density device, and heat conductor installation method of the present invention; Figure 8 This is a schematic structural diagram of a microcirculation unit of a heat conductor according to Example 1 of the micro capillary heat conductor, micro high heat density device, and heat conductor installation method of the present invention; Figure 9 A three-dimensional schematic diagram of a micro-high heat density device according to Example 2 of the micro-capillary heat conductor, micro-high heat density device, and heat conductor installation method of the present invention; Figure 10 This is a schematic structural diagram of a micro-high heat density device according to Example 2 of a micro-capillary heat conductor, a micro-high heat density device, and a heat conductor installation method of the present invention; Figure 11 This is the second structural schematic diagram of a micro-high heat density device according to Example 2 of a micro-capillary heat conductor, a micro-high heat density device, and a heat conductor installation method of the present invention.

[0026] [Description of Reference Numerals] 1. Heat conductor; 11. Housing; 12. Heat conduction module; 1200, heat absorbing surface; 1201, first heat conducting block; 1202, second heat conducting block; 1203, third heat conducting block; 1204, fourth heat conducting block; 121, microcirculation unit; 1210, capillary tube; 12101, heat absorption branch; 12102, evaporation branch; 12103, heat dissipation branch; 12104, connecting pipe; 2. Chip; 3. PCB circuit board; 31. slot; 4. Heat conduction plate; 5. Equipment casing. DETAILED DESCRIPTION

[0027] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below with reference to the accompanying drawings and through specific embodiments. Figure 10 The orientation is used as a reference, with the direction of the chip 2 being "up", the direction of the device housing 5 being "down", the direction parallel to the plane where the chip 2 is located being "horizontal", and the direction perpendicular to the plane where the chip 2 is located being "longitudinal".

[0028] The embodiments of the present invention provide a micro-capillary heat conductor, a micro-high heat density device, and a heat conductor installation method. The heat conductor can be embedded in a PCB circuit board and can conduct heat generated by chip operation from the front side of the PCB circuit board to the back side of the PCB circuit board. The heat conductor includes a housing and a heat conduction module, which is encapsulated in the housing. The heat conduction module includes a first heat conduction block, a second heat conduction block, a third heat conduction block, and a fourth heat conduction block that abut to form a cross-square structure. The first heat conduction block, the second heat conduction block, the third heat conduction block, and the fourth heat conduction block each include several layers of transversely stacked microcirculation units, and each microcirculation unit is filled with a phase change working medium. The microcirculation unit includes a heat absorption area, an evaporation area, and a heat dissipation area that are connected in sequence. The heat absorption zone is used to contact the back of the chip for heat conduction, and the evaporation zone extends downward and outward from the heat absorption zone to the heat dissipation zone. The heat dissipation zone is used to dissipate heat to the back of the PCB circuit board. The area of ​​the heat dissipation zone is larger than that of the heat absorption zone and is located outside the heat absorption zone. Its beneficial effect is that through the microcirculation units of each heat conduction block, the heat generated by the chip can be conducted downward layer by layer and in four directions, providing a large contact area between the fluid and the pipe wall within a unit volume, so that heat can be transferred more quickly from the heat source to the phase change working medium flowing through the channel, resulting in a larger heat conduction area, higher heat conduction efficiency, and stronger heat conduction performance, which solves the technical problem that the existing optical module conducts heat through the PCB vias on the back of the chip and has unsatisfactory heat conduction efficiency.

[0029] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0030] Example 1:

[0031] Reference Figures 1 to 4 This embodiment 1 provides a micro capillary heat conductor. The heat conductor 1 can be embedded in a PCB circuit board 3 and can conduct the heat generated by the chip 2 from the front side of the PCB circuit board 3 to the back side of the PCB circuit board 3.

[0032] The heat conductor 1 includes a housing 11 and a heat conducting module 12, which is encapsulated in the housing 11. The heat conducting module 12 includes a first heat conducting block 1201, a second heat conducting block 1202, a third heat conducting block 1203 and a fourth heat conducting block 1204 that are connected to form a cross-square structure. Figure 1 The first heat-conducting block 1201 and the second heat-conducting block 1202 are arranged along the width direction of the heat conductor 1 and are relatively abutted against each other. The third heat-conducting block 1203 and the fourth heat-conducting block 1204 are relatively arranged along the length direction of the heat conductor 1 and are correspondingly located on both sides of the first heat-conducting block 1201 and the second heat-conducting block 1202, forming a cross-shaped square structure.

[0033] See Figures 5 to 7 The first heat conducting block 1201, the second heat conducting block 1202, the third heat conducting block 1203 and the fourth heat conducting block 1204 are all provided with several layers of microcirculation units 121. The microcirculation units 121 in each heat conducting block are stacked horizontally, and each microcirculation unit 121 is filled with a phase change working medium. The microcirculation unit 121 includes a heat absorption area, an evaporation area and a heat dissipation area connected in sequence. The heat absorption area is used to contact the back side of the chip 2 for heat conduction. The evaporation area extends downward and outward from the heat absorption area to the heat dissipation area. The heat dissipation area is used to dissipate heat to the back side of the PCB circuit board 3. The area of ​​the heat dissipation area is larger than that of the heat absorption area and is located outside the heat absorption area.

[0034] See Figure 5 and Figure 6 The number of the microcirculation units 121 of each heat conducting block is not less than two, and can be two to eight, depending on the size of the chip 2. In this embodiment, each heat conducting block has five microcirculation units 121.

[0035] like Figure 7 and Figure 8As shown, the microcirculation unit 121 includes a plurality of capillaries 1210 arranged side by side and connected together to form a capillary array, and the phase change working medium is perfused into the capillary 1210. The capillary 1210 includes a heat absorption branch 12101, an evaporation branch 12102 and a heat dissipation branch 12103.

[0036] Each capillary 1210 is provided with two evaporation branches 12102, one end of the two evaporation branches 12102 is connected through the heat absorption branch 12101, and the other end of the two evaporation branches 12102 is connected through the heat dissipation branch 12103, forming a closed loop. The evaporation branch 12102 has a stepped structure so that the evaporation areas of two adjacent microcirculation units 121 are stacked together.

[0037] It should be noted that the heat absorption branches 12101 of the capillaries 1210 of the same microcirculation unit 121 are combined together to form a heat absorption area; the evaporation branches 12102 of the capillaries 1210 of the same microcirculation unit 121 are combined together to form an evaporation area; and the heat dissipation branches 12103 of the capillaries 1210 of the same microcirculation unit 121 are combined together to form a heat dissipation area. Figure 4 and Figure 5 The heat absorption areas of each microcirculation unit 121 converge and protrude at the center of the top surface of the thermal module 12, forming a rectangular heat absorption surface 1200 with a compact structure. Heat absorption surface 1200 contacts the bottom surface of chip 2 for heat conduction. The heat dissipation areas of each microcirculation unit 121 converge at the bottom surface of the thermal module 12, forming a heat dissipation surface. Through the evaporation branches 12102, the heat absorption surface 1200 of the thermal module 12 is directly connected to the heat dissipation surface.

[0038] Heat absorbing surface 1200 Figure 1 、 Figure 2 and Figure 4 The area of ​​heat absorbing surface 1200 is greater than or equal to the bottom area of ​​chip 2, and less than the area of ​​the heat dissipating surface. Chip 2 is smaller than slot 31 of PCB 3. Heat from chip 2 is dispersed along the four heat conducting blocks of heat spreader 1 and then transferred to the bottom surface of PCB 3, resulting in a larger heat transfer area and faster heat conduction.

[0039] See Figures 5 to 7The structure and distribution of the microcirculation units 121 of each heat conducting block are consistent. For ease of description, taking the fourth heat conducting block 1204 as an example, the microcirculation unit 121 closest to the second heat conducting block 1202 is named the first unit, and the other four microcirculation units 121 are named the second, third, fourth, and fifth units, respectively. The two evaporation branches 12102 within each microcirculation unit 121 are named the inner branch and outer branch according to their distance from the chip 2. The first unit has an L-shaped cross-section, with the inner branch of the first unit being a straight line, and the outer branch of the first unit being L-shaped and resting on the top surface of the connecting tube 12104. Therefore, the first unit as a whole is L-shaped. The two evaporation branches 12102 within the second, third, fourth, and fifth units are all Z-shaped, consisting of three sections. The first section extends vertically downward, the lower end of the first section bends 90 degrees and then extends outward to form the second section, and the lower end of the second section bends 90 degrees and then extends vertically downward to form the third section. The heights of the first bending points of the evaporation branches 12102 of the second unit, the third unit, the fourth unit and the fifth unit increase, and the heights of their second bending points also increase, and the lengths of the second sections of the evaporation branches 12102 of the second unit, the third unit, the fourth unit and the fifth unit increase. Therefore, the evaporation branches 12102 of these five units are adapted to each other so that each microcirculation unit 121 can be stacked together horizontally, and the tiny heat-absorbing surface 1200 in contact with the chip 2 is changed into a heat-dissipating surface with a larger area, that is, the area of ​​contact and heat dissipation with the device housing 5 described later is greatly increased, and the heat conductor 1 conducts heat along its own length and width directions and downward, and the heat conduction efficiency is higher.

[0040] See Figure 5 and Figure 6, a gap is reserved between the inner branch and the outer branch of the same capillary 1210, and they do not touch each other; in the same microcirculation unit 121, the inner branches of each capillary 1210 are arranged side by side, and the outer branches of each capillary 1210 are arranged side by side; in two adjacent microcirculation units 121, the outer branch of one microcirculation unit 121 is in contact with the inner branch of the other microcirculation unit 121 and is stacked together, so that the inner and outer branches of the first heat conducting block 1201 and the second heat conducting block 1202 are not in contact with each other. The microcirculation units 121 of the heat conductor 1 are stacked together along the width direction of the heat conductor 1, the microcirculation units 121 of the first heat conducting block 1201 and the second heat conducting block 1202 are relatively abutted, and the microcirculation units 121 of the third heat conducting block 1203 and the fourth heat conducting block 1204 are stacked together along the length direction of the heat conductor 1, and the microcirculation units 121 of the third heat conducting block 1203 and the fourth heat conducting block 1204 are relatively placed on both sides of the first heat conducting block 1201 and the second heat conducting block 1202. In actual application, the third heat conducting block 1203 and the fourth heat conducting block 1204 can also be relatively abutted, and the first heat conducting block 1201 and the second heat conducting block 1202 are respectively arranged on both sides of the third heat conducting block 1203 and the fourth heat conducting block 1204.

[0041] During the operation of the heat conductor 1, the phase change fluid at the heat absorption branch 12101 absorbs the heat of the chip 2 and heats up. When the temperature reaches the evaporation condition, the phase change fluid evaporates and rises along the evaporation branch 12102. The vaporized phase change fluid enters the heat dissipation branch 12103, where it liquefies and releases heat when cooled. The heat is then conducted to the bottom surface of the PCB circuit board 3. The liquefied phase change fluid flows back along the evaporation branch 12102 to the heat absorption branch 12101 for the next round of heat conduction process, and the cycle repeats.

[0042] See Figure 6 and Figure 7 As a feasible solution, the microcirculation unit 121 is further provided with a connecting tube 12104, which is connected to each capillary tube 1210. One side of the connecting tube 12104 is connected to the evaporation branch 12102 of each capillary tube 1210, and the other side is connected to the heat dissipation branch 12103 of each capillary tube 1210. The capillary tubes 1210 in each microcirculation unit 121 are connected as a whole through the connecting tube 12104. When the phase change working fluid is injected, it is directly injected into each capillary tube 1210 through the connecting tube 12104, making the injection operation more convenient and faster, and reducing the difficulty of operation.

[0043] It should be noted that during the manufacturing stage of the heat conductor 1, the connecting tube 12104 serves as an infusion line to inject the phase-change working fluid into the microcirculation unit 121. Specifically, after the infusion operation is completed, the connecting tube 12104 is resealed to prevent leakage of the phase-change working fluid and to prevent resin from seeping into the connecting tube 12104 during the lamination process described later. During operation of the heat conductor 1, the connecting tube 12104 accommodates steam from the capillary tubes 1210, providing more space for the steam to release heat, reducing steam pressure within the pipe and increasing the heat dissipation area.

[0044] The heat conductor 1 is provided with a first heat conducting block 1201, a second heat conducting block 1202, a third heat conducting block 1203 and a fourth heat conducting block 1204, so that the heat of the chip 2 is conducted in four directions through the four heat conducting blocks, and since the four heat conducting blocks are in contact with each other, heat can be transferred from the heat conducting block with a higher temperature to the heat conducting block with a lower temperature; in the same heat conducting block, multiple layers of microcirculation units 121 are provided, and the heat absorption area of ​​each microcirculation unit 121 evenly divides the contact surface with the chip 2, so that each microcirculation unit 121 directly conducts the heat of the corresponding position of the chip 2 to the back side of the PCB circuit board 3, and since adjacent microcirculation units 121 are in contact with each other, when there is a temperature difference between the microcirculation units 121, heat can also be transferred from the relatively high temperature place between the microcirculation units 121. Conducted to a place with relatively low temperature; in the same microcirculation unit 121, an array of capillaries 1210 is set, and heat is transferred from the heat absorption branch 12101 of each capillary tube 1210 through the evaporation branch 12102 to the heat dissipation branch 12103. When there is a temperature difference between the capillaries 1210 in the same microcirculation unit 121, heat can be transferred through the connecting pipe 12104 to make the heat of each capillary tube 1210 tend to be averaged; therefore, the heat conductor 1 of the present application forms a capillary heat conduction structure, which provides a large contact area between the phase change medium and the pipe wall within a unit volume. The larger heat conduction area allows heat to be transferred more quickly from the heat source to the phase change medium flowing through the channel, and each point can be efficiently and fully utilized for heat conduction, which helps to significantly reduce the temperature gradient on the surface of the heat source and avoid the occurrence of "hot spots". The heat conductor 1 conducts heat through the phase change medium and can also conduct heat through contact.

[0045] In actual use, the liquid level of the phase-change fluid in capillary tube 1210 is set as needed, generally ranging from one-third to one-half the height of heat conductor 1. Excessive liquid height should be avoided, as this can lead to excessive steam pressure within the pipe and damage capillary tube 1210. Phase-change fluids include, but are not limited to, fluorinated coolants, methanol, or deionized water. The phase-change fluid is injected through connecting tube 12104 and deposited in a small section of the heat absorption branch 12101 and evaporation branch 12102 of each capillary tube 1210.

[0046] See Figure 6 Since the junction of the first heat-conducting block 1201 and the second heat-conducting block 1202 corresponds to the center position of the chip 2, more heat needs to be extracted. Therefore, the two microcirculation units 121 at the junction of the first heat-conducting block 1201 and the second heat-conducting block 1202 are each provided with two connecting pipes 12104. This can increase the heat dissipation space and improve the heat conduction efficiency. At the same time, it can reduce the steam pressure in the pipeline and better cope with the larger heat flux density at the center position of the chip 2.

[0047] See Figure 1 In some feasible solutions, the shell 11 is a rectangular parallelepiped, and the overall shape of the heat conductor 1 corresponds to a rectangular parallelepiped. In actual application, the heat conductor 1 can also be a cube, and the shell 11 corresponds to a cube. The shape of the heat conductor 1 is set according to actual conditions.

[0048] Furthermore, the shell 11 is a cross-shaped square structure adapted to the heat conducting module 12. The overall shape of the heat conductor 1 corresponds to the cross-shaped square structure, which is equivalent to the rectangular heat conductor 1 lacking four right angles. The heat conductor 1 occupies a smaller area, and four corners are reserved in the slot 31 of the PCB circuit board 3 to facilitate the fixation of the heat conductor 1. More wiring positions can also be reserved for the PCB circuit board 3, leaving more layout space for the PCB circuit board 3, reducing the design difficulty of the PCB circuit board 3.

[0049] In actual production applications, both the housing 11 and the heat conducting module 12 are made of materials with high thermal conductivity, such as pure copper, copper alloys, aluminum alloys, or metal-based composite materials, and are 3D printed. The wall thickness of the housing 11 is >0.5 mm. In actual applications, the wall thickness of the housing 11 can be adjusted as needed to ensure that the heat conductor 1 does not deform after lamination.

[0050] Heat conductor 1 is suitable for dissipating heat from miniature devices with high heat density. In this embodiment, chip 2 can be a TIA (transimpedance amplifier) ​​chip in an optical module. The internal space of an optical module is small, and the front of the TIA chip needs to be connected to optical components and wiring on the PCB 3. Therefore, the space available for heat conductor 1 is very small. Therefore, this application designs heat conductor 1 to be very small, and incorporates a large number of capillaries 1210 within the microcirculation unit 121 of the extremely small heat conductor 1. This microcapillary heat conductor 1 is embedded in the PCB 3 and in contact with the back of the TIA chip for heat conduction, resulting in high thermal efficiency and excellent thermal conductivity. Chip 2 can also be any other chip in the optical module.

[0051] It's important to note that due to its high thermal efficiency and compact size, heat conductor 1 is not only suitable for dissipating heat from optical modules, but also for dissipating heat from other miniature, high-heat-density devices, such as radar systems and computing chips like CPUs and GPUs. Within a very limited space, heat conductor 1 efficiently and evenly transfers the intense, concentrated heat generated by chip 2, ensuring stable, reliable, and high-performance operation within a safe temperature range while meeting the requirements for miniaturization, lightweighting, and low noise.

[0052] Example 2:

[0053] Reference Figures 9 to 11 This embodiment 2 provides a micro high heat density device, including but not limited to an optical module, a radar system, etc. The micro high heat density device includes a device housing 5, a PCB circuit board 3, a chip 2, and the heat conductor 1 of embodiment 1.

[0054] See Figure 9 and Figure 10 The PCB 3 is placed in the device housing 5, with the bottom surface of the PCB 3 abutting against the device housing 5. The PCB 3 defines a slot 31, and the heat spreader 1 is completely embedded in the slot 31. The chip 2 is placed on the top surface of the heat spreader 1 and soldered to the PCB 3. The heat spreader 1 and the chip 2 are in contact and heat transfer, thereby transferring the heat of the chip 2 to the device housing 5. The device housing 5 is usually made of metal with good thermal conductivity.

[0055] See Figure 11 In some feasible solutions, a heat conducting plate 4 is provided between the PCB circuit board 3 and the device housing 5. The heat conducting plate 4 is made of a material with a high thermal conductivity, such as a copper plate.

[0056] When no components are required on the front of the chip 2 , a commercially available heat sink can be installed on the front of the chip 2 to assist in heat dissipation. The heat sink adopts existing technology and will not be described in detail here.

[0057] The process flow of embedding the heat conductor 1 into the PCB circuit board 3 is as follows: S1. Slot design: Use a precision numerical control (CNC) machine tool to mill out a slot 31 on the inner core board or prepreg of the PCB circuit board 3 . The slot 31 is used to place the heat conductor 1 .

[0058] Thermal analysis is required before slotting: based on the power, position and desired temperature target of the heating element, the position, size and thickness of the heat conductor 1 to be embedded are determined.

[0059] The size of the slot 31 is usually slightly larger than the heat conductor 1 itself (a gap of 0.05 to 0.1 mm is reserved on one side) to leave space for resin flow during subsequent lamination and to avoid the heat conductor 1 being unable to be embedded due to milling accuracy.

[0060] Prepreg is a resin pre-impregnated material (without a copper layer), and slotting will not damage the PCB circuit. During lamination, the molten resin can flow to fill the gap between the slot wall and the heat spreader 1, and after curing, it forms a mechanical locking structure. If slotting is performed in the inner core board, circuit detours or isolation areas must be designed in advance.

[0061] S2. The shell 11 of the heat conductor 1 is subjected to browning or blackening treatment to form a microscopically rough oxide layer (usually a mixture of Cu2O and / or CuO) on the outer surface of the shell 11 of the heat conductor 1.

[0062] Browning treatment uses an alkaline oxidizing solution (such as NaClO2) at 60-80°C for 5-10 minutes to generate Cu2O. Acidic blackening (such as a NaClO2-H2SO4 system) partially converts this to CuO. Browning or blackening treatment significantly increases the contact surface area and mechanical engagement between the heat spreader 1 and the PCB resin (prepreg), significantly improving the bond between the two and preventing delamination during subsequent processing or use. The microscopically rough surface created by the browning / blackening treatment forms a strong mechanical bond with the cured resin.

[0063] S3. Stacking and Placing Copper Blocks: Align and stack the inner core board, prepreg, and copper foil layers with slots 31 cut in them according to the designed stack-up structure. During the stacking process, the processed heat spreader 1 is precisely placed into the pre-milled slots 31, either manually or using automated equipment.

[0064] Before proceeding to step S3, connection design is required: large copper-clad areas (usually connected to the ground layer or power layer) are designed on the upper and lower layers of the PCB copper foil on the top and bottom surfaces of the embedded position of the heat conductor 1 to thermally connect the heat conductor 1 to the conductive layer of the PCB. The copper foil anchors the heat conductor 1 to prevent displacement and can also quickly conduct heat from the heat conductor 1 to other areas of the PCB circuit board 3.

[0065] S4, lamination: The stacked sheets with the heat conductor 1 placed thereon are fed into a vacuum laminator and laminated under high temperature and high pressure conditions to obtain an integrated finished structure of the PCB circuit board 3 and the heat conductor 1.

[0066] During vacuum lamination, the prepreg melts at 180-200°C, and the resin flows under a pressure of 200-300 psi to fill the gaps in the slots 31 and wrap around the browned surface of the shell 11 of the heat conductor 1. After curing, a mechanical interlocking structure is formed, making the heat conductor 1 and the PCB circuit board 3 an integrated finished product structure.

[0067] After curing, the sheet material is laminated to form a complete PCB circuit board 3. The top and bottom layers of the PCB circuit board 3 are copper foil layers, which cover the top and bottom surfaces of the heat conductor 1 respectively. The heat conductor 1 is embedded in the finished PCB circuit board 3. In other words, the heat conductor 1 is encapsulated in the PCB circuit board 3.

[0068] In actual applications, a prepreg with a high resin content (RC ≥ 55%) is generally used; after lamination, the heat conductor 1 is inspected to confirm that there is no resin infiltration or deformation in the capillary 1210 .

[0069] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0070] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0071] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0072] In the description of this specification, the terms "one embodiment", "some embodiments", "embodiments", "examples", "specific examples" or "some examples" refer to the specific features, structures, materials or characteristics described in conjunction with the embodiment or example and included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0073] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A micro capillary heat conductor, characterized in that: The heat conductor (1) can be embedded in a PCB circuit board (3) and can conduct heat generated by the operation of the chip (2) from the front side of the PCB circuit board (3) to the back side of the PCB circuit board (3). The heat conductor (1) comprises a housing (11) and a heat conduction module (12), and the heat conduction module (12) is encapsulated in the housing (11). The heat conduction module (12) comprises a first heat conduction block (1201), a second heat conduction block (1202), a third heat conduction block (1203) and a fourth heat conduction block (1204) which are abutted to form a cross-square structure; the first heat conduction block (1201), the second heat conduction block (1202), the third heat conduction block (1203) and the fourth heat conduction block (1204) each comprise a plurality of layers of transversely stacked microcirculation units (121), and each of the microcirculation units (121) is filled with a phase change working medium; The microcirculation unit (121) comprises a heat absorption zone, an evaporation zone and a heat dissipation zone which are connected in sequence. The heat absorption zone is used to contact the back of the chip (2) for heat conduction. The evaporation zone extends downward and outward from the heat absorption zone to the heat dissipation zone. The heat dissipation zone is used to dissipate heat to the back of the PCB circuit board (3). The area of ​​the heat dissipation zone is larger than that of the heat absorption zone and is located outside the heat absorption zone.

2. A micro capillary heat conductor according to claim 1, characterized in that: The heat absorption areas of the microcirculation units (121) are aggregated and raised in the middle area of ​​the top surface of the heat conduction module (12) to form a rectangular heat absorption surface (1200), and the heat dissipation areas of the microcirculation units (121) are aggregated on the bottom surface of the heat conduction module (12) to form a heat dissipation surface.

3. A micro capillary heat conductor according to claim 2, characterized in that: The microcirculation unit (121) comprises a plurality of capillaries (1210) arranged side by side and connected together, a phase change working medium is perfused into the capillaries (1210), the capillaries (1210) comprise a heat absorption branch (12101), an evaporation branch (12102) and a heat dissipation branch (12103), all the heat absorption branches (12101) in the microcirculation unit (121) are aggregated into the heat absorption zone, all the evaporation branches (12102) in the microcirculation unit (121) constitute the evaporation zone, and all the heat dissipation branches (12103) in the microcirculation unit (121) are aggregated into the heat dissipation zone; Each of the capillary tubes (1210) is provided with two evaporation branches (12102), one end of the two evaporation branches (12102) is connected via a heat absorption branch (12101), and the other end of the two evaporation branches (12102) is connected via a heat dissipation branch (12103), forming a closed loop. The evaporation branches (12102) are of a stepped structure so that the evaporation areas of adjacent microcirculation units (121) are stacked together.

4. A micro capillary heat conductor according to claim 3, characterized in that: A gap is reserved between the two evaporation branches (12102) of the same capillary tube (1210) so that they do not contact each other.

5. The micro capillary heat conductor according to claim 4, characterized in that: The microcirculation unit (121) is further provided with a connecting pipe (12104) for perfusing a phase-change working medium. The connecting pipe (12104) is connected to each of the capillaries (1210). One side of the connecting pipe (12104) is connected to the evaporation branch (12102) of each capillary tube (1210), and the other side is connected to the heat dissipation branch (12103) of each capillary tube (1210).

6. The micro capillary heat conductor according to claim 5, characterized in that: The microcirculation unit (121) at the junction of the first heat-conducting block (1201) and the second heat-conducting block (1202) is provided with two connecting pipes (12104).

7. The micro capillary heat conductor according to claim 1, characterized in that: The housing (11) is a rectangular parallelepiped, or a cross-shaped square structure adapted to the heat conduction module (12).

8. A micro high heat density device, characterized in that: It comprises a device housing (5), a PCB circuit board (3), a chip (2), and a micro capillary heat conductor according to any one of claims 1 to 7; The PCB circuit board (3) is placed in the device housing (5), and the bottom surface of the PCB circuit board (3) is in contact with the device housing (5). The PCB circuit board (3) is provided with a slot (31), and the heat conductor (1) is embedded in the slot (31). The chip (2) is provided on the top surface of the heat conductor (1) and is welded to the PCB circuit board (3). The heat conductor (1) contacts the chip (2) for heat conduction, so as to conduct the heat of the chip (2) to the device housing (5).

9. The micro high heat density device according to claim 8, characterized in that: A heat conducting plate (4) is provided between the PCB circuit board (3) and the device housing (5).

10. A method for installing a heat conductor, characterized in that: The method for embedding the heat conductor (1) according to any one of claims 1 to 7 on a PCB circuit board (3) comprises the following steps: S1, milling out a slot (31) for placing the heat conductor (1) on the inner core board or prepreg of the PCB circuit board (3); S2, performing browning or blackening treatment on the shell (11) of the heat conductor (1) to form a rough oxide layer on the outer surface of the shell (11) of the heat conductor (1); S3, aligning and stacking the sheet materials including the inner core board with the slots (31), the prepreg and the copper foil layer according to the preset stacking structure, and placing the heat conductor (1) after browning or blackening treatment into the pre-milled slots (31); S4. The sheet material is fed into a vacuum laminator and laminated under high temperature and high pressure conditions to obtain an integrated finished structure of the PCB circuit board (3) and the heat conductor (1).

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