Microcapillary heat conductor, micro high heat density device and heat conductor mounting method

Abstract

The application belongs to the technical field of optical communication, and relates to a micro capillary heat conductor, a micro high-heat-density device and a heat conductor mounting method. The heat conductor comprises a shell and a heat conduction module encapsulated 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. The first heat conduction block, the second heat conduction block, the third heat conduction block and the fourth heat conduction block each comprise a plurality of layers of micro circulation units, and each micro circulation unit is filled with phase change working medium. The micro circulation unit comprises a heat absorption zone, an evaporation zone and a heat dissipation zone which are sequentially communicated. The heat absorption zone is used for heat conduction with the back surface of the chip. The evaporation zone extends downward and outward from the heat absorption zone to the heat dissipation zone. The heat dissipation zone is used for dissipating heat to the back surface of the PCB circuit board. The area of the heat dissipation zone is greater than that of the heat absorption zone, and the heat dissipation zone is located outside the heat absorption zone. The beneficial effect is that the technical problem of the existing optical module which conducts heat through the PCB via hole on the back surface of the chip and has an unsatisfactory heat conduction efficiency is solved.

Description

TECHNICAL FIELD

[0001] The present application 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 mounting method. BACKGROUND

[0002] In the process of heat dissipation of the optical module, the main ways of heat transfer from the optical module to the system include heat conduction, heat convection and heat radiation. The optical module is small in size and belongs to a micro device, and cannot use forced convection (such as a fan), and mainly relies on heat conduction to conduct the heat of the optical module to the shell and then dissipate it in the form of convection.

[0003] In the optical module, the heat dissipation design of the TIA (transimpedance amplifier) chip faces unique challenges: the front surface needs to be connected to the optical path assembly by gold wires, and cannot be directly contacted and dissipated by the shell, so the heat dissipation path mainly relies on the PCB heat conduction design of the back surface of the chip. The current mainstream solutions include three ways: hollow via, solid via and copper-filled via. The hollow via solution is to drill a hole in the PCB, then plate copper on the hole wall, keep the middle hollow, and rely on the copper layer on the hole wall for heat conduction; the solid via solution is to completely fill the via with copper to form a solid copper column, providing a continuous vertical heat conduction path; the copper-filled via solution is to fill the via with high-thermal-conductivity materials (such as copper paste, silver paste or resin mixed materials), rather than pure copper. However, the heat conduction efficiency of these heat conduction solutions is not very ideal.

[0004] Therefore, it is necessary to design a heat conduction device suitable for micro devices to efficiently dissipate heat from the heat-generating chip. SUMMARY

[0005] (I) Technical problems to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present application provides a micro capillary heat conductor, a micro high-heat-density device and a heat conductor mounting method, which solves the technical problem that the existing optical module conducts heat through the PCB via on the back surface of the chip, and the heat conduction efficiency is not ideal.

[0007] (II) Technical solutions

[0008] In order to achieve the above-mentioned purposes, the main technical solutions adopted by the present application include:

[0009] In a first aspect, the embodiments of the present application provide a micro-capillary heat conduction device, which can be embedded in a PCB circuit board and can conduct heat generated by a chip from the front surface of the PCB circuit board to the back surface of the PCB circuit board. The heat conduction device comprises a shell and a heat conduction module, and the heat conduction module is encapsulated 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 abutting to form a cross-shaped square structure. The first heat conduction block, the second heat conduction block, the third heat conduction block and the fourth heat conduction block each comprise a plurality of layers of micro-recycling units stacked in a transverse direction, and each micro-recycling unit is filled with a phase change working medium. The micro-recycling unit comprises a heat absorption zone, an evaporation zone and a heat dissipation zone connected in sequence. The heat absorption zone is used to contact the back surface 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 surface of the PCB circuit board. The area of the heat dissipation zone is greater than the area of the heat absorption zone, and the heat dissipation zone is located outside the heat absorption zone.

[0010] Optionally, the heat absorption zones of the micro-recycling units are aggregated and protrude in the middle region of the top surface of the heat conduction module to form a rectangular heat absorption surface. The heat dissipation zones of the micro-recycling units are aggregated to form a heat dissipation surface on the bottom surface of the heat conduction module.

[0011] Optionally, the micro-recycling unit comprises a plurality of capillary tubes arranged side by side and connected together. The phase change working medium is filled in the capillary tubes. The capillary tube comprises a heat absorption branch, an evaporation branch and a heat dissipation branch. All the heat absorption branches in the micro-recycling unit are aggregated to form the heat absorption zone. All the evaporation branches in the micro-recycling unit form the evaporation zone. All the heat dissipation branches in the micro-recycling unit are aggregated to form the heat dissipation zone.

[0012] Each capillary tube is provided with two evaporation branches. One end of the two evaporation branches is connected through the heat absorption branch. The other end of the two evaporation branches is connected through the heat dissipation branch to form a closed cycle. The evaporation branch is in a stepped structure so that the evaporation zones of adjacent micro-recycling units are stacked together.

[0013] Optionally, a gap is reserved between the two evaporation branches of the same capillary tube, and the two evaporation branches do not contact each other.

[0014] Optionally, the micro-recycling unit is further provided with a communication pipe for filling the phase change working medium. The communication pipe is connected with each capillary tube. One side of the communication pipe is connected with the evaporation branch of each capillary tube, and the other side of the communication pipe is connected with the heat dissipation branch of each capillary tube.

[0015] Optionally, the micro-recycling unit at the joint of the first heat conduction block and the second heat conduction block is provided with two communication pipes.

[0016] Optionally, the shell is a rectangular parallelepiped or a cross-shaped square structure matched with the heat conduction module.

[0017] In a second aspect, the embodiment of the present application provides a micro high-heat-density device, comprising a device shell, a PCB circuit board, a chip and the micro capillary heat conductor as described above; the PCB circuit board is arranged in the device shell, and the bottom surface of the PCB circuit board is in abutment with the device shell; the PCB circuit board is provided with a slot, the heat conductor is embedded in the slot, the chip is arranged on the top surface of the heat conductor and is welded with the PCB circuit board, and the heat conductor is in contact with the chip to conduct heat of the chip to the device shell.

[0018] Optionally, a heat-conducting plate is arranged between the PCB circuit board and the device shell.

[0019] In a third aspect, the embodiment of the present application provides a heat conductor mounting method for embedding the heat conductor as described above on the PCB circuit board, comprising the following steps:

[0020] S1, milling a slot for placing the heat conductor on an inner core plate or a prepreg of the PCB circuit board;

[0021] S2, performing brown or black treatment on the shell of the heat conductor to form a rough oxide layer on the outer surface of the shell of the heat conductor;

[0022] S3, aligning and stacking the plate material including the inner core plate with the milled slot, the prepreg and the copper foil layer according to a preset stacking structure, and placing the heat conductor subjected to the brown or black treatment into the pre-milled slot;

[0023] S4, feeding the plate material into a vacuum laminating machine to perform lamination under high temperature and high pressure to obtain an integrated product structure of the PCB circuit board and the heat conductor.

[0024] (Three) beneficial effects

[0025] The beneficial effects of the present application are:

[0026] 1. The micro capillary heat conductor, the micro high-heat-density device and the heat conductor mounting method of the present application, since the heat-conducting module adopts the cross-shaped block structure composed of the first heat-conducting block, the second heat-conducting block, the third heat-conducting block and the fourth heat-conducting block, and each heat-conducting block adopts the stacked arrangement of multiple micro circulation units, the heat generated by the chip can be conducted downward and in four directions layer by layer through the micro circulation units of each heat-conducting block, a great contact area of fluid and pipe wall surface is provided in a unit volume, so that the heat can be transmitted more rapidly from the heat source to the phase-change working medium flowing through the channel, the heat-conducting area is larger, the heat-conducting efficiency is higher, and the heat-conducting performance is stronger, compared with the prior art, the technical problem of the prior art that the heat is conducted through the PCB via hole on the back surface of the chip of the optical module and the heat-conducting efficiency is not ideal is solved.

[0027] 2. Due to the high thermal conductivity of heat conductors, they can handle higher heat flux density per unit area, thus reducing their size. This makes them suitable for small, highly integrated products with concentrated heat generation and high power, such as optical modules, radar systems, and computing chips like CPUs or GPUs. Within extremely limited space, they can quickly and evenly transfer the massive, highly concentrated heat generated by electronic devices or systems with extremely high efficiency (compared to traditional heat dissipation methods), ensuring that the equipment operates stably, reliably, and with high performance within a safe temperature range, while also meeting the requirements for miniaturization, lightweight design, and low noise.

[0028] 3. The micro-circulation unit is printed using 3D printing technology. It includes multiple capillaries arranged side by side and connected together. The capillaries are connected and aggregated through connecting tubes to form a capillary heat conduction structure. The capillary heat conduction structure is closely arranged below or around the heat source. When the phase change working fluid flows through these channels, it can carry away heat more directly and evenly, which helps to significantly reduce the temperature gradient on the surface of the heat source and avoid the formation of "hot spots", thereby improving the reliability, stability and performance of the equipment.

[0029] 4. The heat-conducting module printed using 3D printing technology comprises multiple heat-conducting blocks, each stacked with multiple micro-circulation units. Each micro-circulation unit contains multiple capillaries, thus integrating a large number of heat dissipation channels within a very small space, achieving extremely high heat dissipation density (heat dissipation capacity per unit volume). This makes the overall device design more compact and lightweight, especially suitable for space-constrained applications such as laptops, smartphones, drones, and satellites.

[0030] 5. Due to its small size, the heatsink can be directly embedded in any position on the PCB circuit board, making the installation position flexible, occupying less area, leaving more space for PCB circuit board layout, and reducing the design difficulty of the PCB circuit board.

[0031] 6. The micro-circulation unit is equipped with multiple capillaries, which are connected by a connecting pipe. Each capillary has two evaporation branches. The phase change working fluid is stored in the heat absorption branch and absorbs heat there. After absorbing heat, the phase change working fluid evaporates. The vaporized phase change working fluid moves along the two evaporation branches to the heat dissipation branch, where it liquefies upon cooling. The liquefied phase change working fluid then flows back to the heat absorption branch along the two evaporation branches. Therefore, the heat conductor has better operational stability and its heat conduction operation will not be affected by blockage in any one branch.

[0032] 7. The evaporation zone of the micro-circulation unit is designed with a stepped structure, which allows two adjacent micro-circulation units to be stacked together, increases the length of the heat conduction path, increases the heat conduction area, and improves the heat conduction and heat dissipation effect.

[0033] 8. The capillary tubes of the micro circulation unit are unified perfused with phase change working medium through the communication pipe, and the operation is more convenient.

[0034] 9. The heat conduction device is directly embedded into the PCB circuit board, and the risk of product failure caused by complex punching process can be avoided. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Fig. 1 is a perspective view of the heat conduction device of Embodiment 1 of the micro capillary heat conduction device, micro high heat density device and heat conduction device installation method of the present application;

[0036] Figure 2 Fig. 2 is a perspective view of the heat conduction device of Embodiment 1 of the micro capillary heat conduction device, micro high heat density device and heat conduction device installation method of the present application (without showing the shell);

[0037] Figure 3 Fig. 3 is a perspective view of the heat conduction device of Embodiment 1 of the micro capillary heat conduction device, micro high heat density device and heat conduction device installation method of the present application (without showing the shell);

[0038] Figure 4 Fig. 4 is a front view of the heat conduction device of Embodiment 1 of the micro capillary heat conduction device, micro high heat density device and heat conduction device installation method of the present application;

[0039] Figure 5 Fig. 5 is a bottom view of the heat conduction device of Embodiment 1 of the micro capillary heat conduction device, micro high heat density device and heat conduction device installation method of the present application;

[0040] Figure 6 Fig. 6 is a sectional view of the first heat conduction block and the second heat conduction block of the heat conduction device of Embodiment 1 of the micro capillary heat conduction device, micro high heat density device and heat conduction device installation method of the present application;

[0041] Figure 7 Fig. 7 is a sectional view of the fourth heat conduction block of the heat conduction device of Embodiment 1 of the micro capillary heat conduction device, micro high heat density device and heat conduction device installation method of the present application;

[0042] Figure 8 Fig. 8 is a structural view of the micro circulation unit of the heat conduction device of Embodiment 1 of the micro capillary heat conduction device, micro high heat density device and heat conduction device installation method of the present application;

[0043] Figure 9 Fig. 9 is a perspective view of the micro high heat density device of Embodiment 2 of the micro capillary heat conduction device, micro high heat density device and heat conduction device installation method of the present application;

[0044] Figure 10Fig. 2 is a schematic diagram of a micro high heat density device structure according to an embodiment of the micro capillary heat conductor, micro high heat density device and heat conductor installation method of the present application;

[0045] Figure 11 Fig. 3 is another schematic diagram of a micro high heat density device structure according to an embodiment of the micro capillary heat conductor, micro high heat density device and heat conductor installation method of the present application.

[0046] [Legend of Reference Signs]

[0047] 1. Heat conductor; 11. Shell; 12. Heat conducting module;

[0048] 1200. Heat absorbing surface; 1201. First heat conducting block; 1202. Second heat conducting block; 1203. Third heat conducting block; 1204. Fourth heat conducting block;

[0049] 121. Micro circulation unit; 1210. Capillary tube; 12101. Heat absorbing branch; 12102. Evaporation branch; 12103. Heat dissipation branch; 12104. Connecting tube;

[0050] 2. Chip;

[0051] 3. PCB circuit board; 31. Slot;

[0052] 4. Heat conducting plate;

[0053] 5. Device shell. DETAILED DESCRIPTION

[0054] In order to better explain the present application, so as to be understood, the present application is described in detail below by specific embodiments, in combination with the accompanying drawings. In this article, the orientation of the mentioned "up", "down" and other orientation terms is referred to the orientation of the chip 2 as "up", the orientation of the device shell 5 as "down", the orientation parallel to the plane of the chip 2 as "lateral", and the orientation perpendicular to the plane of the chip 2 as "vertical". Figure 10

[0055] ​The micro-capillary heat conductor, the micro-high heat density device and the heat conductor mounting method provided by the embodiment of the present application can be embedded in a PCB circuit board and can conduct the heat generated by the operation of a chip from the front surface of the PCB circuit board to the back surface of the PCB circuit board. The heat conductor comprises a shell and a heat conduction module, and the heat conduction module is 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 which 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 comprise a plurality of layers of micro circulation units stacked in the transverse direction, and each micro circulation unit is filled with a phase change working medium. The micro circulation unit comprises a heat absorption zone, an evaporation zone and a heat dissipation zone which are sequentially connected. The heat absorption zone is used for conducting heat in contact with the back surface of the chip. The evaporation zone extends downward and outward from the heat absorption zone to the heat dissipation zone. The heat dissipation zone is used for dissipating heat to the back surface of the PCB circuit board. The area of the heat dissipation zone is greater than that of the heat absorption zone and is located outside the heat absorption zone. The beneficial effects are that the heat generated by the chip can be conducted layer by layer downward and in four directions through the micro circulation units of the heat conduction blocks, a large contact area of fluid and pipe wall surface is provided in a unit volume, heat can be more quickly transferred from the heat source to the phase change working medium flowing through the channel, the heat conduction area is larger, the heat conduction efficiency is higher, and the heat conduction performance is stronger. The technical problem that the heat conduction efficiency is not ideal when the existing optical module conducts heat through the PCB via hole on the back surface of the chip is solved.

[0056] In order to better understand the above technical solutions, the exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer, more thorough understanding of the present application and to convey the scope of the present application to those skilled in the art.

[0057] Embodiment 1:

[0058] With reference to Figures 1 to 4 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 operation of a chip 2 from the front surface of the PCB circuit board 3 to the back surface of the PCB circuit board 3.

[0059] The heat conductor 1 comprises a shell 11 and a heat conduction module 12, and the heat conduction module 12 is packaged in the shell 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 abut to form a cross-square structure. Referring to Figure 1The first heat-conducting block 1201 and the second heat-conducting block 1202 are arranged along the width direction of the heat-conducting device 1 and abut against each other, and the third heat-conducting block 1203 and the fourth heat-conducting block 1204 are arranged along the length direction of the heat-conducting device 1 and are located on both sides of the first heat-conducting block 1201 and the second heat-conducting block 1202, forming a cross-shaped block structure.

[0060] Referring to 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 each provided with a plurality of micro circulation units 121, the micro circulation units 121 in each heat-conducting block are stacked transversely, and each micro circulation unit 121 is filled with a phase change working medium. The micro circulation unit 121 comprises a heat absorption zone, an evaporation zone and a heat dissipation zone which are sequentially connected. The heat absorption zone is used for contacting the back surface 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 for dissipating heat to the back surface of the PCB circuit board 3. The area of the heat dissipation zone is greater than that of the heat absorption zone and is located outside the heat absorption zone.

[0061] Referring to Figure 5 and Figure 6 The number of the micro circulation units 121 of each heat-conducting block is not less than two, which can be two to eight, according to the size of the chip 2. In this embodiment, the micro circulation units 121 of each heat-conducting block are provided with five.

[0062] As shown in Figure 7 and Figure 8 , the micro circulation unit 121 comprises a plurality of capillary tubes 1210 arranged side by side and connected together, forming a capillary tube array, and the phase change working medium is filled in the capillary tubes 1210. The capillary tube 1210 comprises a heat absorption branch 12101, an evaporation branch 12102 and a heat dissipation branch 12103.

[0063] Each capillary tube 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 circulation. The evaporation branch 12102 is in a stepped structure so that the evaporation zones of adjacent two micro circulation units 121 are stacked together.

[0064] It should be noted that the heat absorption branches 12101 of the capillary tubes 1210 of the same micro circulation unit 121 are combined to form the heat absorption zone; the evaporation branches 12102 of the capillary tubes 1210 of the same micro circulation unit 121 are combined to form the evaporation zone; and the heat dissipation branches 12103 of the capillary tubes 1210 of the same micro circulation unit 121 are combined to form the heat dissipation zone. Referring to Figure 4 and Figure 5, the heat absorption areas of each microcirculation unit 121 are gathered together and protrude in the center area of the top surface of the heat conduction module 12, forming a rectangular heat absorption surface 1200, which is compact in structure. The heat absorption surface 1200 is in contact with the bottom surface of the chip 2 for heat conduction. The heat dissipation areas of each microcirculation unit 121 are gathered together in the bottom surface of the heat conduction module 12, forming a heat dissipation surface, and the heat absorption surface 1200 of the heat conduction module 12 is in direct convection with the heat dissipation surface through each evaporation branch 12102.

[0065] The heat absorption surface 1200 is shown in dashed lines in Figure 1 , Figure 2 and Figure 4 . The area of the heat absorption surface 1200 is greater than the area of the bottom surface of the chip 2, and the area of the heat absorption surface 1200 is less than the area of the heat dissipation surface. The size of the chip 2 is smaller than the size of the slot 31 of the PCB circuit board 3, and the heat of the chip 2 is dispersed in the direction of the four heat conduction blocks of the heat conduction device 1, and then conducted to the bottom surface of the PCB circuit board 3, so that the heat conduction area is larger and the heat conduction speed is faster.

[0066] Referring to Figures 5 to 7 , the structure and distribution of the microcirculation units 121 of each heat conduction block are consistent. For the convenience of description, the fourth heat conduction block 1204 is taken as an example, the microcirculation units 121 close to the second heat conduction block 1202 are named as the first unit, and the other four microcirculation units 121 are sequentially named as the second unit, the third unit, the fourth unit and the fifth unit. The two evaporation branches 12102 in each microcirculation unit 121 are named as the inner side branch and the outer side branch according to the distance from the chip 2. Among them, the cross section of the first unit is L-shaped, the inner side branch of the first unit is a straight line, the outer side branch of the first unit is L-shaped and is placed on the top surface of the communication pipe 12104, so the first unit as a whole is L-shaped. The two evaporation branches 12102 in the second unit, the third unit, the fourth unit and the fifth unit are Z-shaped as a whole, including 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, the lower end of the second section bends 90 degrees and then extends vertically downward to form the third section. The height of the first bending point of the evaporation branch 12102 of the second unit, the third unit, the fourth unit and the fifth unit increases, the height of the second bending point of them also increases, and the length of the second section of the evaporation branch 12102 of the second unit, the third unit, the fourth unit and the fifth unit also increases, so the evaporation branches 12102 of the five units adapt to each other, so that each microcirculation unit 121 can be stacked together laterally, the micro heat absorption surface 1200 in contact with the chip 2 becomes a heat dissipation surface with a larger area, that is, the area of the contact heat dissipation with the equipment shell 5 described later is greatly increased, and the heat conduction device 1 conducts heat along the length and width directions of itself and downward, so the heat conduction efficiency is higher.

[0067] Referring to Figure 5 andFigure 6 The inner side branch and the outer side branch of the same capillary 1210 are reserved with a gap and do not contact each other; in the same micro circulation unit 121, the inner side branches of the capillaries 1210 are arranged side by side, and the outer side branches of the capillaries 1210 are arranged side by side; in the adjacent two micro circulation units 121, the outer side branch in one of the micro circulation units 121 and the inner side branch of the other micro circulation unit 121 are contacted and stacked together, each micro circulation unit 121 in the first heat conducting block 1201 and the second heat conducting block 1202 is stacked together along the width direction of the heat conducting device 1, the micro circulation units 121 of the first heat conducting block 1201 and the second heat conducting block 1202 are relatively abutted, each micro circulation unit 121 in the third heat conducting block 1203 and the fourth heat conducting block 1204 is stacked together along the length direction of the heat conducting device 1, and the micro circulation units 121 of the third heat conducting block 1203 and the fourth heat conducting block 1204 are relatively arranged on the two sides of the first heat conducting block 1201 and the second heat conducting block 1202. In actual application process, 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 separately arranged on the two sides of the third heat conducting block 1203 and the fourth heat conducting block 1204.

[0068] In the working process of the heat conducting device 1, the phase change working medium at the heat absorbing branch 12101 absorbs the heat of the chip 2 and is heated, when the temperature reaches the evaporation condition, the phase change working medium evaporates and rises along the evaporation branch 12102, the vaporized phase change working medium enters the heat dissipation branch 12103 and is liquefied to release heat, and the heat is conducted to the bottom surface of the PCB circuit board 3, the liquefied phase change working medium flows back to the heat absorbing branch 12101 along the evaporation branch 12102 to perform the next round of heat conducting process, and the circulation is repeated.

[0069] Referring to Figure 6 and Figure 7 As a feasible scheme, the micro circulation unit 121 is further provided with a communication pipe 12104, the communication pipe 12104 is communicated with each capillary 1210, one side of the communication pipe 12104 is communicated with the evaporation branch 12102 of each capillary 1210, and the other side is communicated with the heat dissipation branch 12103 of each capillary 1210. Each capillary 1210 in each micro circulation unit 121 is connected into a whole through the communication pipe 12104, when the phase change working medium is filled, the phase change working medium is directly filled into each capillary 1210 through the communication pipe 12104, the filling operation is more convenient and faster, and the operation difficulty is lower.

[0070] It should be noted that, in the manufacturing stage of the heat conductor 1, the communication pipe 12104 is used as a filling pipe to fill the phase change working medium into the micro circulation unit 121. In particular, after the filling operation is completed, the communication pipe 12104 is resealed to ensure that the phase change working medium does not leak and that the resin does not penetrate into the communication pipe 12104 during the subsequent lamination. During the operation of the heat conductor 1, the communication pipe 12104 can accommodate the vapor of each capillary tube 1210, provide more space for the vapor to release heat, reduce the vapor pressure in the pipe, and increase the heat dissipation area.

[0071] 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, the 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 micro circulation units 121 are arranged, and the heat absorption area of each micro circulation unit 121 is divided into a contact surface with the chip 2, so that each micro circulation unit 121 directly conducts the heat of the corresponding position of the chip 2 to the back surface of the PCB circuit board 3, and since adjacent micro circulation units 121 are in contact with each other, when there is a temperature difference between each micro circulation unit 121, the heat can also be conducted from a relatively high temperature place to a relatively low temperature place between the micro circulation units 121; in the same micro circulation unit 121, an array of capillary tubes 1210 is arranged, and the heat is conducted from the heat absorption branch 12101 of each capillary tube 1210 to the heat dissipation branch 12103 through the evaporation branch 12102, and when there is a temperature difference between each capillary tube 1210 of the same micro circulation unit 121, the heat can be conducted through the communication pipe 12104 to make the heat of each capillary tube 1210 tend to be average; therefore, the heat conductor 1 of the present application forms a capillary heat conducting structure, which provides a large contact area between the phase change working medium and the pipe wall in a unit volume, has a larger heat conducting area, so that the heat can be more quickly transferred from the heat source to the phase change working 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 of the heat source surface and avoid the occurrence of "hot spots". The heat conductor 1 conducts heat through the phase change working medium, and at the same time, the heat can also be conducted through contact.

[0072] In actual application, the liquid level of the phase change working medium in the capillary tube 1210 is set according to the needs, and the liquid level is generally between one-third and one-half of the height of the heat conductor 1. The liquid level should not be too high, otherwise the vapor pressure in the pipe will be too high and the capillary tube 1210 will be damaged. The phase change working medium includes but is not limited to fluorinated coolant, methanol, or deionized water. The phase change working medium is injected from the communication pipe 12104 and stored in a small position of the heat absorption branch 12101 and the evaporation branch 12102 of each capillary tube 1210.

[0073] Referring to 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 dissipated, and therefore both microcirculation units 121 at the junction of the first heat-conducting block 1201 and the second heat-conducting block 1202 are provided with two communicating pipes 12104, so as to increase the heat dissipation space and improve the heat conduction efficiency, while reducing the vapor pressure in the pipes, so as to better cope with the greater heat flux density at the center position of the chip 2.

[0074] Referring to Figure 1 In some feasible solutions, the shell 11 is a cuboid, and the overall shape of the heat-conducting device 1 corresponds to a cuboid. In actual application, the heat-conducting device 1 can also be a square, and the shell 11 corresponds to a square. The shape of the heat-conducting device 1 is set according to actual conditions.

[0075] Further, the shell 11 is a cross-shaped square structure that is adapted to the heat-conducting module 12. The overall shape of the heat-conducting device 1 corresponds to a cross-shaped square structure, which is equivalent to a cuboid that lacks four right angles. The heat-conducting device 1 occupies a smaller area, and four corners are reserved in the slot 31 of the PCB circuit board 3, which facilitates the fixation of the heat-conducting device 1. In addition, the heat-conducting device 1 can reserve more wiring positions for the PCB circuit board 3, so as to provide a larger layout space for the PCB circuit board 3 and reduce the design difficulty of the PCB circuit board 3.

[0076] In actual production and application, the shell 11 and the heat-conducting module 12 are made of materials with high heat conductivity, such as pure copper, copper alloy, aluminum alloy, and metal matrix composite materials, and are printed by 3D printing technology. The wall thickness of the shell 11 is greater than 0.5 mm. In actual application, the wall thickness parameter of the shell 11 can be adjusted according to actual needs to ensure that the heat-conducting device 1 does not deform after lamination.

[0077] The heat-conducting device 1 is suitable for dissipating heat from a miniature device with high heat density. In this embodiment, the chip 2 can be a TIA (transimpedance amplifier) chip of an optical module. The internal space of the optical module is small, and the front surface of the TIA chip needs to be connected to an optical assembly. Wiring is required on the PCB circuit board 3, so the space available for the heat-conducting device 1 is very small. Therefore, the volume of the heat-conducting device 1 is designed to be very small, and a large number of capillary tubes 1210 are designed in the microcirculation unit 121 of the very small heat-conducting device 1. The miniature capillary heat-conducting device 1 is embedded in the PCB circuit board 3 and contacts the back surface of the TIA chip for heat conduction, so as to achieve high heat conduction efficiency and good heat conduction effect. The chip 2 can also be other chips of an optical module.

[0078] It should be noted that, due to the high heat conduction efficiency and small volume of the heat conduction device 1, it is not only suitable for heat dissipation of optical modules, but also can be used for heat dissipation of other miniature high heat density devices, such as radar systems, CPU or GPU computing chips, etc. In the extremely limited space, the heat conduction device 1 quickly and uniformly transfers the highly concentrated and huge heat generated by the chip 2 with extremely high efficiency, ensures the stable, reliable and high-performance operation of the device within the safe temperature range, and meets the requirements of miniaturization, light weight and low noise of the device.

[0079] Embodiment 2:

[0080] With reference to Figures 9 to 11 , this embodiment 2 provides a miniature high heat density device, including but not limited to optical modules, radar systems, etc. The miniature high heat density device includes a device shell 5, a PCB circuit board 3, a chip 2 and the heat conduction device 1 of embodiment 1.

[0081] With reference to Figure 9 and Figure 10 , the PCB circuit board 3 is placed in the device shell 5, and the bottom surface of the PCB circuit board 3 abuts against the device shell 5. The PCB circuit board 3 is provided with a slot 31, and the heat conduction device 1 is completely embedded in the slot 31. The chip 2 is placed on the top surface of the heat conduction device 1 and is welded with the PCB circuit board 3. The heat conduction device 1 is in contact with the chip 2 to conduct the heat of the chip 2 to the device shell 5. The device shell 5 is usually made of metal material with good heat conduction.

[0082] With reference to Figure 11 , in some feasible solutions, a heat conduction plate 4 is arranged between the PCB circuit board 3 and the device shell 5. The heat conduction plate 4 is made of material with high heat conduction coefficient, such as copper plate.

[0083] When the front surface of the chip 2 does not need to be provided with any component, a heat sink available on the market can be installed on the front surface of the chip 2 to assist heat dissipation. The heat sink adopts existing technology and is not described in detail here.

[0084] The process flow of embedding the heat conduction device 1 into the PCB circuit board 3 is as follows:

[0085] S1, slot design: a precise numerical control machine tool (CNC) is used to mill a slot 31 on the inner layer core plate or semi-solid sheet of the PCB circuit board 3. The slot 31 is used to place the heat conduction device 1.

[0086] Before slotting, thermal analysis needs to be performed: based on the power, position and expected temperature target of the heat generating element, the position, size and thickness of the heat conduction device 1 to be embedded are determined.

[0087] The size of the slot 31 is usually slightly larger than the heat conductor 1 itself (single side reserved 0.05-0.1mm gap), to leave room for resin flow during subsequent lamination, avoiding the heat conductor 1 from being unable to be embedded due to milling accuracy.

[0088] The prepreg is a resin pre-impregnated material (without copper layer), and the 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 conductor 1, and after solidification, a mechanical locking structure is formed; if the inner layer core board is slotted, the circuit needs to be designed in advance to bypass or isolate the area.

[0089] S2, the shell 11 of the heat conductor 1 is subjected to brown or black treatment, and a microscopically rough oxide layer (usually a mixture of Cu2O and / or CuO) is formed on the outer surface of the shell 11 of the heat conductor 1.

[0090] The brown treatment adopts alkaline oxidizing liquid (such as NaClO2), and Cu2O is generated by reacting at 60-80℃ for 5-10 minutes, and then acid blackening (such as NaClO2-H2SO4 system) is performed to partially convert Cu2O to CuO. The brown or black treatment greatly increases the contact surface area and mechanical engagement force between the heat conductor 1 and the PCB resin (prepreg), thereby significantly improving the bonding force between the two, preventing delamination during subsequent processing or use. The microscopically rough surface formed after the brown / black treatment cooperates with the cured resin to form a strong mechanical bonding force.

[0091] S3, stack and place copper block: align and stack the inner layer core board with slotted slot 31, prepreg and copper foil layer according to the designed stack-up structure. During the stacking process, the treated heat conductor 1 is accurately placed in the pre-milled slot 31 by hand or using automated equipment.

[0092] Before step S3, connection design is also needed: a large area of copper area (usually connected to the ground layer or power layer) is designed on the top and bottom layers of PCB copper foil at the embedding position of the heat conductor 1, so that the heat conductor 1 is in thermal contact with the conductive layer of the PCB, and the heat conductor 1 is anchored by the copper foil to prevent displacement, and the heat can also be quickly conducted from the heat conductor 1 to other areas of the PCB circuit board 3.

[0093] S4, lamination: the stacked and placed heat conductor 1 is sent to a vacuum laminator for lamination under high temperature and pressure conditions, and an integrated product structure of the PCB circuit board 3 and the heat conductor 1 is obtained.

[0094] When vacuum laminating, the prepreg melts at 180-200℃, the resin flows to fill the gap of the slot 31 under the pressure of 200-300 psi, and wraps the surface of the shell 11 of the heat conduction device 1 which has been browned; after curing, a mechanical interlocking structure is formed, so that the heat conduction device 1 and the PCB circuit board 3 become an integrated product structure.

[0095] After curing, the plate material becomes the complete product of the PCB circuit board 3 after lamination, and the top and bottom layers of the PCB circuit board 3 are copper foil layers corresponding to the top and bottom surfaces of the heat conduction device 1, and the heat conduction device 1 is embedded in the product of the PCB circuit board 3, in other words, the heat conduction device 1 is packaged in the PCB circuit board 3.

[0096] In actual application, prepregs with high resin content (RC≥55%) are generally used; after lamination, the heat conduction device 1 is detected to confirm that there is no resin infiltration or deformation in the capillary tube 1210.

[0097] In the description of the present application, it should be understood that the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0098] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0099] In the present application, unless otherwise specifically defined and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature, can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature, can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is lower than that of the second feature.

[0100] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0101] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can modify, modify, replace and modify the above-described embodiments within the scope of the present application.

Claims

1. A microcapillary heat conductor, characterized by: The heat conduction device (1) can be embedded in a PCB circuit board (3) and can conduct heat generated by the chip (2) from the front of the PCB circuit board (3) to the back of the PCB circuit board (3), and the heat conduction device (1) comprises a shell (11) and a heat conduction module (12), and the heat conduction module (12) is encapsulated in the shell (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) abutting 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) all comprise a plurality of layers of micro circulation units (121) stacked transversely, and each of the micro circulation units (121) is filled with a phase change working medium; The micro circulation unit (121) comprises a heat absorption zone, an evaporation zone and a heat dissipation zone connected in sequence, the heat absorption zone is used for contacting 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, and the heat dissipation zone is used for dissipating heat to the back of the PCB circuit board (3), the area of the heat dissipation zone is greater than the area of the heat absorption zone, and the heat dissipation zone is located outside the heat absorption zone.

2. A microcapillary heat conductor as claimed in claim 1, characterized in that: The heat absorption zones of the micro circulation units (121) are aggregated and protrude in the middle region of the top surface of the heat conduction module (12) to form a rectangular heat absorption surface (1200), and the heat dissipation zones of the micro circulation units (121) are aggregated to form a heat dissipation surface on the bottom surface of the heat conduction module (12).

3. A microcapillary heat conductor as claimed in claim 2, characterized in that: The micro circulation unit (121) comprises a plurality of capillary tubes (1210) arranged side by side and connected together, the phase change working medium is filled in the capillary tubes (1210), the capillary tubes (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 micro circulation unit (121) are aggregated into the heat absorption zone, all the evaporation branches (12102) in the micro circulation unit (121) constitute the evaporation zone, and all the heat dissipation branches (12103) in the micro circulation unit (121) are aggregated into the heat dissipation zone; Each of the evaporation branches (12102) of the capillary tube (1210) is provided with two, one end of the two evaporation branches (12102) is connected through the heat absorption branch (12101), the other end of the two evaporation branches (12102) is connected through the heat dissipation branch (12103), a closed loop is formed, and the evaporation branch (12102) is in a stepped structure, so that the evaporation zones of adjacent micro circulation units (121) are stacked together.

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

5. A microcapillary heat conductor as claimed in claim 4, characterized in that: The micro circulation unit (121) is further provided with a communication pipe (12104) for filling phase change working medium, the communication pipe (12104) is communicated with each capillary pipe (1210), one side of the communication pipe (12104) is communicated with the evaporation branch (12102) of each capillary pipe (1210), and the other side is communicated with the heat dissipation branch (12103) of each capillary pipe (1210).

6. A microcapillary heat conductor as claimed in claim 5, characterized in that: The micro circulation unit (121) at the joint of the first heat conduction block (1201) and the second heat conduction block (1202) is provided with two communication pipes (12104).

7. A microcapillary heat conductor as defined in claim 1, wherein: The shell (11) is a rectangular parallelepiped, or a cross-shaped square block structure matched with the heat conduction module (12).

8. A micro high heat density device characterized by: The micro heat conduction device comprises a device shell (5), a PCB circuit board (3), a chip (2) and a micro capillary heat conduction device as claimed in any one of claims 1 to 7. The PCB circuit board (3) is arranged in the device shell (5), and the bottom surface of the PCB circuit board (3) is in abutment with the device shell (5). The PCB circuit board (3) is provided with a slot (31), the heat conduction device (1) is embedded in the slot (31), and the chip (2) is arranged on the top surface of the heat conduction device (1) and is welded to the PCB circuit board (3). The heat conduction device (1) is in contact with the chip (2) to conduct heat, so that the heat of the chip (2) is conducted to the device shell (5).

9. A micro high heat density device as claimed in claim 8, characterized by: A heat conduction plate (4) is arranged between the PCB circuit board (3) and the device shell (5).

10. A heat conducting device mounting method characterized by comprising: The heat conduction device (1) as claimed in any one of claims 1 to 7 is embedded on the PCB circuit board (3), comprising the following steps: S1, milling a slot (31) for placing the heat conduction device (1) on the inner core board or prepreg of the PCB circuit board (3); S2, performing brown or black treatment on the shell (11) of the heat conduction device (1) to form a rough oxide layer on the outer surface of the shell (11) of the heat conduction device (1); S3, aligning and stacking the board material including the inner core board, the prepreg and the copper foil layer with a preset stacking structure, and placing the heat conduction device (1) subjected to the brown or black treatment into the pre-milled slot (31); S4, feeding the board material into a vacuum laminating machine to perform lamination under high temperature and high pressure conditions, so as to obtain an integrated finished product structure of the PCB circuit board (3) and the heat conduction device (1).

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