Embedded type heat dissipation channel composite printed circuit board and preparation method thereof

Abstract

The invention provides an embedded type heat dissipation channel composite printed circuit board and a preparation method thereof, the embedded type heat dissipation channel composite printed circuit board comprises a heat conduction insulation substrate, the heat conduction insulation substrate comprises an upper substrate, a lower substrate, an upper metal heat conduction layer and a lower metal heat conduction layer, the middle part of the lower surface of the upper substrate is provided with a plurality of transverse main channels; a plurality of vertical drainage channels are formed in the middle of the upper surface of the lower substrate; according to the composite printed circuit board, the upper substrate, the lower substrate, the upper metal heat conduction layer and the lower metal heat conduction layer are made of the aluminum oxide ceramic substrate, so that the composite printed circuit board has excellent insulation performance and relatively high heat conductivity, the comprehensive mechanical performance is improved, heat is dissipated into the main channel and the drainage channel, and the service life of the composite printed circuit board is prolonged. Flowing air makes full contact with the surface of the metal heat conduction layer in the heat dissipation channel, heat is taken away through heat convection, and therefore overheating of the interior of the circuit board is avoided, and the operation stability and the AI calculation efficiency of the circuit board are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of circuit boards, and particularly relates to a buried heat dissipation channel composite printed circuit board and a preparation method thereof. BACKGROUND

[0002] As a common type of printed circuit board (PCB), a double-layer circuit board plays a key role in electronic devices, and its basic structure is that both surfaces of an insulating substrate are covered with conductive copper layers, namely a top copper layer and a bottom copper layer. Since the wiring space of the double-layer circuit board is doubled, more components can be accommodated, and more complex circuits can be supported, and compared with multi-layer boards, the design and manufacturing costs are more moderate, so the double-layer circuit board is widely used.

[0003] However, as electronic devices and AI functions become more powerful, the main circuit components generate more heat, especially AI computing, which generates more heat on the circuit board. Since the conventional circuit board is insufficient to meet the heat dissipation requirement, when the heat generated inside the circuit board cannot be dissipated in time, the temperature of the circuit board will rise, which will further reduce the performance of electronic components, cause unstable operation, abnormal signal transmission and other problems, and seriously affect the efficiency of AI computing. SUMMARY

[0004] (1) Technical problem to be solved In view of the deficiencies of the prior art, the purpose of the present application is to provide a buried heat dissipation channel composite printed circuit board and a preparation method thereof, so as to solve the problem that when the heat generated by the existing AI computing circuit board cannot be dissipated in time, the temperature of the circuit board will rise, which will further reduce the performance of electronic components, cause unstable operation, abnormal signal transmission and other problems, and affect the efficiency of AI computing.

[0005] (2) Technical scheme In order to solve the above technical problems, the present application provides a buried heat dissipation channel composite printed circuit board, which comprises a heat-conducting insulating substrate, the heat-conducting insulating substrate comprises an upper substrate, a lower substrate, an upper metal heat-conducting layer and a lower metal heat-conducting layer, a plurality of horizontal main channels are formed in the middle of the lower surface of the upper substrate, and a plurality of vertical drainage channels are formed in the middle of the upper surface of the lower substrate; the upper metal heat-conducting layer and the lower metal heat-conducting layer are fixedly connected inside the main channels and the drainage channels through heat-conducting glue, the upper metal heat-conducting layer and the lower metal heat-conducting layer are fixedly welded, and the upper substrate and the lower substrate are respectively covered with an upper circuit layer and a lower circuit layer on the side away from each other.

[0006] Preferably, the upper substrate and the lower substrate are both alumina ceramic substrates.

[0007] Preferably, the upper and lower metal heat-conducting layers are integrally bent and formed from copper material, and a plurality of heat dissipation grooves are formed on one side of the upper and lower metal heat-conducting layers inside the main channel and the flow channel.

[0008] Preferably, a heat dissipation opening is formed in the middle of the upper substrate, the heat dissipation opening penetrates the upper metal heat-conducting layer and communicates with the main channel, and an avoiding opening corresponding to the heat dissipation opening is formed on the upper circuit layer.

[0009] Preferably, the heat-conducting glue is polysiloxane silicone glue.

[0010] Preferably, mounting holes are formed at four corners of the upper surface of the upper substrate, and the other end of the mounting hole penetrates the lower substrate.

[0011] Preferably, a plurality of upper micro-channels and a plurality of lower micro-channels are respectively formed on the upper substrate and the lower substrate, one end of the upper micro-channels and the lower micro-channels respectively communicates with the main channel and the flow channel, and the other end of the upper micro-channels and the lower micro-channels respectively extends to the high-power components of the upper circuit layer and the lower circuit layer.

[0012] Preferably, an upper flow guide spherical cavity is formed at the intersection of the upper micro-channel and the main channel, and a lower flow guide spherical cavity is formed at the intersection of the lower micro-channel and the flow channel.

[0013] Preferably, the width of the main channel and the flow channel is greater than the height, the width of the main channel and the flow channel is 5-8mm, the height of the main channel and the flow channel is 2-3mm, and the inner wall of the main channel and the flow channel is plated with copper foil.

[0014] Preferably, a preparation method of a buried heat dissipation channel composite printed circuit board comprises the following steps: Step one, high-purity alumina ceramic powder is selected as raw material, and the green body of the upper substrate and the lower substrate is respectively pressed to form the main channel and the flow channel, and a layer of copper foil is covered on the outer surface of the upper substrate and the lower substrate through the hot-pressing sintering process; Step two, the copper skin is cut according to the actual size of the main channel and the flow channel, and the upper and lower metal heat-conducting layers which are adapted to the main channel and the flow channel are prepared by pressure casting; Step three, the upper and lower metal heat-conducting layers are aligned in a transverse intersection manner at ninety degrees, and are welded and fixed by brazing process, and the upper substrate, the lower substrate, the upper metal heat-conducting layer and the lower metal heat-conducting layer are assembled and placed into a pressing equipment to realize stable combination; Step four, photoresist is coated on the surface of the copper foil, and the required circuit layer is obtained through exposure, development and etching process, and a through hole is formed to realize reliable electrical communication between the upper and lower circuit layers, and the preparation of the composite printed circuit board is completed.

[0015] Compared with the prior art, the present application has the beneficial effects that: (1) In the above scheme, the heat-conducting insulating substrate composed of the upper substrate, the lower substrate and the upper metal heat-conducting layer and the lower metal heat-conducting layer made of aluminum oxide ceramic substrate makes the composite printed circuit board have excellent insulating performance and high thermal conductivity, improves the comprehensive mechanical properties, and the aluminum oxide ceramic can quickly conduct heat to ensure that the temperature of each part of the circuit board is uniform and the heat is dissipated into the main channel and the flow channel, the flowing air fully contacts the surface of the metal heat-conducting layer in the heat dissipation channel, and the heat is taken away through convection heat exchange, thereby avoiding overheating of the internal circuit board and improving the operation stability of the circuit board. (2) In the above scheme, the heat dissipation channel on the composite printed circuit board is divided into a main channel and a flow channel, which realizes ventilation and heat dissipation from four sides of the composite printed circuit board, not only increases the contact area and flow path of air and the circuit board, but also enables the heat to be taken away more quickly, and the middle part of the upper substrate is provided with a heat dissipation opening in communication with the main channel, which can form natural air circulation. In some cases where the heat dissipation requirement is not high or the space is limited and cannot install a fan or other forced heat dissipation equipment, the heat dissipation effect is good, the temperature of each part of the circuit board is uniform, and the performance degradation problem caused by local overheating is avoided. (3) In the above scheme, the upper micro-channel and the lower micro-channel are respectively formed in the upper substrate and the lower substrate, and are respectively connected with the main channel and the flow channel of the high-power components, thereby facilitating heat conduction and increasing the contact area. At the same time, the inner walls of the main channel and the flow channel are plated with copper foil, thereby increasing the contact area and strengthening the synergistic progress of the structure function and rapid heat conduction. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a schematic diagram of the perspective structure of the embedded heat dissipation channel composite printed circuit board. Figure 2 It is a schematic diagram of the exploded structure of the embedded heat dissipation channel composite printed circuit board. Figure 3 It is a schematic diagram of the front view structure of the embedded heat dissipation channel composite printed circuit board. Figure 4 It is a schematic diagram of the embedded heat dissipation channel composite printed circuit board. Figure 3 It is a schematic diagram of the enlarged structure of position A in the embedded heat dissipation channel composite printed circuit board. Figure 5 It is a schematic diagram of the front view structure of the embedded heat dissipation channel composite printed circuit board. Figure 6 It is a schematic diagram of the embedded heat dissipation channel composite printed circuit board. Figure 5 It is a schematic diagram of the enlarged structure of position B in the embedded heat dissipation channel composite printed circuit board. Figure 7Fig. 2 is a schematic view of a right side sectional structure of a composite printed circuit board with embedded heat dissipation channels; Figure 8 Fig. 3 is a schematic view of a left side sectional structure of a composite printed circuit board with embedded heat dissipation channels; Figure 7 Fig. 4 is a schematic view of an enlarged structure at C in Fig. 3; The reference signs in the drawings are as follows: 2, upper substrate; 3, lower substrate; 4, upper metal heat conduction layer; 5, lower metal heat conduction layer; 6, main channel; 7, flow guide channel; 8, heat conduction adhesive; 9, upper circuit layer; 10, lower circuit layer; 11, heat dissipation groove; 12, heat dissipation opening; 13, avoidance opening; 14, mounting hole; 21, upper micro channel; 22, lower micro channel; 23, upper flow guide spherical cavity; 24, lower flow guide spherical cavity. DETAILED DESCRIPTION

[0017] The application will be further described below in conjunction with the drawings and specific embodiments: Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application; the description and claims herein contain provisions relating to compositions, structures, and methods of the present application, and are intended to cover and encompass various modifications and embodiments of the application. The description and claims herein contain provisions relating to compositions, structures, and methods of the present application, and are intended to cover and encompass various modifications and embodiments of the application. The terms "comprise", "comprising", "include", "including", "have", "has", "contain", "containing", or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, or method that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, process, or method. The terms "first", "second", "third", "fourth", "fifth", "sixth", "a", "an", "the", and "said", used in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a specific sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of use in either order.

[0018] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to one or more of the same embodiments. It is expressly understood that any of the embodiments described herein can be incorporated into any other embodiment.

[0019] The embodiment of the application provides a composite printed circuit board with embedded heat dissipation channels, which comprises a heat-conducting insulating substrate, the heat-conducting insulating substrate comprises an upper substrate 2, a lower substrate 3, an upper metal heat conduction layer 4 and a lower metal heat conduction layer 5, the upper substrate 2 and the lower substrate 3 are both alumina ceramic substrates, a plurality of horizontal main channels 6 are formed in the middle of the lower surface of the upper substrate 2, a plurality of vertical flow guide channels 7 are formed in the middle of the upper surface of the lower substrate 3, the cross sections of the main channels 6 and the flow guide channels 7 are rectangular, the two ends of the main channels 6 and the flow guide channels 7 are rounded, the rounding is used for eliminating the hindrance of sharp edges to airflow, reducing the vortex phenomenon of airflow at the ends of the channels, and improving the heat exchange efficiency of airflow circulation, wherein the thermal conductivity of the alumina ceramic substrate is greater than or equal to 30 W / (m·K), which can meet the heat dissipation requirement.

[0020] The upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5 are fixedly connected to the inside of the main channel 6 and the flow channel 7 respectively by the heat-conducting glue 8, the heat-conducting glue 8 is a polysiloxane organic silicone glue material, which can be used for heat dissipation and fixation, the upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5 are fixed by welding, the welding position forms a continuous metal heat-conducting connection without heat resistance breakpoint, which ensures the rapid heat transfer between the upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5, realizes the heat exchange cooperation of the main channel and the flow channel, the upper substrate 2 and the lower substrate 3 are covered with the upper circuit layer 9 and the lower circuit layer 10 respectively on the side away from each other, when the circuit board works, the heat is transferred to the upper substrate 2, the lower substrate 3, the upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5 through heat conduction, since the alumina ceramic substrate and the metal both have good heat-conducting performance, the heat can be rapidly diffused to the whole circuit board and dissipated into the main channel 6 and the flow channel 7, in the case of installing a fan and other forced heat dissipation equipment outside, the forced air flow generated by the fan rapidly passes through the heat dissipation channel, the flowing air fully contacts the surface of the metal heat-conducting layer in the heat dissipation channel, and the heat is taken away through the convection heat exchange.

[0021] As shown in Figure 1 and Figure 2 , in the present embodiment, the upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5 are integrally bent and formed by copper material, a plurality of heat dissipation grooves 11 are arranged on the side of the upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5 inside the main channel 6 and the flow channel 7; the contact area with air is increased through the plurality of heat dissipation grooves 11, and the heat dissipation is better.

[0022] As shown in Figures 1-4 , in the present embodiment, the middle part of the upper substrate 2 is provided with a heat dissipation opening 12, the heat dissipation opening 12 penetrates the upper metal heat-conducting layer 4 and communicates with the main channel 6, and the upper circuit layer 9 is provided with an avoiding opening 13 corresponding to the heat dissipation opening 12; in this way, when the circuit board works, the heat is transferred to the upper substrate 2, the lower substrate 3, the upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5 through heat conduction, since the alumina ceramic substrate and the metal both have good heat-conducting performance, the heat can be rapidly diffused to the whole circuit board and dissipated into the main channel 6 and the flow channel 7, in the case of natural convection, since the air in the heat dissipation channel expands and the density decreases due to heating, the hot air rises and flows out from the heat dissipation opening 12, and the cold air is supplemented from one end of the heat dissipation channel, forming natural air circulation, in the case of not installing a fan and other forced heat dissipation equipment due to the limited space or not particularly high requirement for heat dissipation, the heat dissipation effect is good.

[0023] In order to facilitate the installation of the circuit board, as shown in Figure 2 and Figure 3 , in the present embodiment, the upper surface of the upper substrate 2 is provided with installation holes 14 at four corners, and the other end of the installation hole 14 penetrates the lower substrate 3.

[0024] AsFigures 5-8 As shown, in this embodiment, multiple upper microchannels 21 and multiple lower microchannels 22 are respectively formed on the upper substrate 2 and the lower substrate 3. One end of the upper microchannel 21 and the lower microchannel 22 are connected to the main channel 6 and the drainage channel 7, respectively. The other end of the upper microchannel 21 and the lower microchannel 22 extend to the high-power components of the upper circuit layer 9 and the lower circuit layer 10, respectively, avoiding the conductive lines of the upper circuit layer 9 and the lower circuit layer 10, and precisely corresponding to the heat-generating area of ​​the high-power components, realizing the directional heat dissipation and avoiding heat loss. The components are stacked around the components; an upper guide spherical cavity 23 is provided at the intersection of the upper microchannel 21 and the main channel 6, and a lower guide spherical cavity 24 is provided at the intersection of the lower microchannel 22 and the drainage channel 7, which facilitates heat conduction and drainage. The interior of the upper guide spherical cavity 23 and the lower guide spherical cavity 24 is a smooth curved surface, which can eliminate the dead airflow at the junction of the upper microchannel 21 and the main channel 6, and the lower microchannel 22 and the drainage channel 7, while reducing the resistance loss when the airflow turns, so that the airflow flows smoothly and improves the continuity of local heat dissipation.

[0025] like Figure 2 and Figure 3 As shown, in this embodiment, the width of both the main channel 6 and the drainage channel 7 is greater than their height. The width of both the main channel 6 and the drainage channel 7 is 5-8 mm, and the height of both the main channel 6 and the drainage channel 7 is 2-3 mm. The inner walls of both the main channel 6 and the drainage channel 7 are plated with copper foil.

[0026] This invention also proposes a method for fabricating an embedded heat dissipation channel composite printed circuit board as described above, comprising the following steps: Step 1: Select high-purity alumina ceramic powder as raw material, press it into blanks of upper substrate 2 and lower substrate 3 respectively, and form main channel 6, flow channel 7 and mounting hole 14. Then process the blanks by hot pressing sintering process, and cover the outer surface of upper substrate 2 and lower substrate 3 with a layer of copper foil. Then open heat dissipation port 12 and clearance port 13 on upper substrate 2 for later use. Step 2: Based on the actual dimensions of the main channel 6 and the drainage channel 7, cut out copper sheets with perfectly matching specifications using a cutting device. Then, process heat dissipation grooves 11 on the surface of the copper sheets using CNC machining equipment according to the dimensions. During the cutting process, ensure that the edges of the copper sheets are flat and burr-free to avoid affecting the subsequent forming effect. Then, die-cast the upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5 to match the main channel 6 and the drainage channel 7. Make holes on the upper metal heat-conducting layer 4 that correspond to the heat dissipation vents 12. After processing, clean the surface of the metal heat-conducting layer to remove oil, oxide layer and processing debris. The hot pressing temperature is 1500-1800℃, the pressure is 20-50MPa, and the holding time is 2-4 hours to ensure that the ceramic substrate reaches the required density and mechanical strength. Step three, align the upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5 in a transverse crossing manner at 90 degrees, and use the brazing process to weld and fix, then uniformly coat the inner walls and mounting surfaces of the upper substrate 2 and the lower substrate 3 corresponding to the heat dissipation channels with the heat-conducting glue 8, the coating thickness needs to be controlled within 0.1-0.3mm, ensuring uniform coating, no leakage, and no accumulation, then precisely embed the welded and fixed upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5 into the main channel 6 and the drainage channel 7 respectively, and finally put the assembled upper substrate 2, lower substrate 3, upper metal heat-conducting layer 4 and lower metal heat-conducting layer 5 into the pressing equipment to realize stable combination. Step four, coat the copper foil surface with photoresist, obtain the required circuit layer through the exposure, development and etching process, then drill holes in the four corners of the upper substrate 2 and the lower substrate 3 using a drilling device to form through holes, the drilling diameter is designed according to the through requirement, usually 0.2-0.8mm, the drilling avoids the heat dissipation channel, then fill the through hole with conductive material to realize reliable electrical communication between the upper circuit layer 9 and the lower circuit layer 10, according to the use environment and reliability requirements of the circuit board, finally process the surface of the upper and lower circuit layers, common processing methods include hot air leveling, chemical nickel gold, organic solderability preservative, etc., to improve the solderability, oxidation resistance and wear resistance of the circuit layer, and complete the preparation of the composite printed circuit board.

[0027] In this embodiment, in step three, the copper-phosphorus filler material matched with copper is selected for welding, the welding temperature is controlled within 700-800℃, to ensure that the welding joint is firm, without virtual welding and pores, and after welding, the residual filler material in the welding seam is cleaned, the preset pressure of the pressing equipment is 5-15MPa, and is maintained for 30-60 minutes, while the environmental temperature is controlled within 25-50℃, to ensure that the heat-conducting glue 8 is fully cured.

[0028] The technical scheme provided by the present application uses the heat-conducting and insulating substrate composed of the upper substrate 2 and the lower substrate 3 made of aluminum oxide ceramic substrate and the upper metal heat-conducting layer 4 and the lower metal heat-conducting layer 5, so that the composite printed circuit board has excellent insulation performance and high thermal conductivity, improves the comprehensive mechanical properties, and the aluminum oxide ceramic can quickly conduct heat to ensure that the temperature of each part of the circuit board is uniform, and the heat is dissipated into the main channel 6 and the drainage channel 7, the flowing air fully contacts the surface of the metal heat-conducting layer in the heat dissipation channel, and the heat is taken away through convection heat exchange, thereby avoiding overheating of the circuit board and improving the operation stability of the circuit board.

[0029] The present application encompasses any alternatives, modifications, equivalent methods and solutions made to the spirit and scope of the present application. In order to make the public have a thorough understanding of the present application, the specific details are described in the above preferred embodiments of the present application, and the present application can be fully understood without the description of these details to those skilled in the art. In addition, in order to avoid unnecessary confusion to the essence of the present application, well-known methods, processes, procedures, elements and circuits, etc. are not described in detail.

[0030] Those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment methods can be completed by programs instructing the relevant hardware, and the programs can be stored in computer-readable storage media, such as ROM / RAM, magnetic disc, optical disc, etc.

[0031] The above is only the preferred embodiment of the present application, and it should be pointed out that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A composite printed circuit board with embedded heat dissipation channels, characterized in that, The substrate includes a thermally conductive insulating substrate, which includes an upper substrate (2), a lower substrate (3), an upper metal thermally conductive layer (4), and a lower metal thermally conductive layer (5). The lower surface of the upper substrate (2) has multiple horizontal main channels (6) in the middle, and the upper surface of the lower substrate (3) has multiple vertical drainage channels (7) in the middle. The upper metal thermally conductive layer (4) and the lower metal thermally conductive layer (5) are fixedly connected to the interior of the main channels (6) and the drainage channels (7) respectively by thermally conductive adhesive (8). The upper metal thermally conductive layer (4) and the lower metal thermally conductive layer (5) are welded and fixed. The sides of the upper substrate (2) and the lower substrate (3) that are far apart are covered with an upper circuit layer (9) and a lower circuit layer (10) respectively.

2. The embedded heat dissipation channel composite printed circuit board according to claim 1, characterized in that, Both the upper substrate (2) and the lower substrate (3) are alumina ceramic substrates.

3. The embedded heat dissipation channel composite printed circuit board according to claim 1, characterized in that, The upper metal heat-conducting layer (4) and the lower metal heat-conducting layer (5) are both integrally bent from copper. The upper metal heat-conducting layer (4) and the lower metal heat-conducting layer (5) are provided with multiple heat dissipation grooves (11) on one side inside the main channel (6) and the drainage channel (7).

4. The embedded heat dissipation channel composite printed circuit board according to claim 3, characterized in that, A heat dissipation port (12) is provided in the middle of the upper substrate (2). The heat dissipation port (12) penetrates the upper metal heat-conducting layer (4) and is connected to the main channel (6). An avoidance port (13) corresponding to the heat dissipation port (12) is provided on the upper circuit layer (9).

5. The embedded heat dissipation channel composite printed circuit board according to claim 1, characterized in that, The thermally conductive adhesive (8) is a polysiloxane silicone adhesive.

6. The embedded heat dissipation channel composite printed circuit board according to claim 4, characterized in that, Mounting holes (14) are provided at the four corners of the upper surface of the upper substrate (2), and the other end of the mounting holes (14) passes through the lower substrate (3).

7. The embedded heat dissipation channel composite printed circuit board according to claim 2, characterized in that, Multiple upper microchannels (21) and multiple lower microchannels (22) are respectively provided on the upper substrate (2) and the lower substrate (3). One end of the upper microchannel (21) and the lower microchannel (22) are connected to the main channel (6) and the drainage channel (7) respectively. The other end of the upper microchannel (21) and the lower microchannel (22) extends to the high power consumption components of the upper circuit layer (9) and the lower circuit layer (10) respectively.

8. The embedded heat dissipation channel composite printed circuit board according to claim 7, characterized in that, An upper guide spherical cavity (23) is provided at the intersection of the upper microchannel (21) and the main channel (6), and a lower guide spherical cavity (24) is provided at the intersection of the lower microchannel (22) and the drainage channel (7).

9. The embedded heat dissipation channel composite printed circuit board according to claim 1, characterized in that, The width of the main channel (6) and the drainage channel (7) is greater than the height. The width of the main channel (6) and the drainage channel (7) is 5-8mm. The height of the main channel (6) and the drainage channel (7) is 2-3mm. The inner walls of the main channel (6) and the drainage channel (7) are plated with copper foil.

10. A method for preparing an embedded heat dissipation channel composite printed circuit board as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Select high-purity alumina ceramic powder as raw material, press it into blanks of upper substrate (2) and lower substrate (3) respectively, and form main channel (6) and flow channel (7). Process the blanks by hot pressing sintering process, and cover the outer surface of upper substrate (2) and lower substrate (3) with a layer of copper foil. Step 2: Cut copper foil according to the actual dimensions of the main channel (6) and the drainage channel (7), and die-cast it to make an upper metal heat-conducting layer (4) and a lower metal heat-conducting layer (5) that are compatible with the main channel (6) and the drainage channel (7). Step 3: Align the upper metal heat-conducting layer (4) and the lower metal heat-conducting layer (5) at a 90-degree angle in a horizontal cross manner, and fix them by brazing. After assembling the upper substrate (2), the lower substrate (3), the upper metal heat-conducting layer (4) and the lower metal heat-conducting layer (5), place them into the pressing equipment to achieve a stable bond. Step 4: Coat the copper foil surface with photoresist, and obtain the required circuit layer through exposure, development and etching processes, and form conductive vias to achieve reliable electrical connection between the upper circuit layer (9) and the lower circuit layer (10), thus completing the preparation of the composite printed circuit board.

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