A preparation method of a cantilever type embedded microchannel printed circuit board

Abstract

The present invention relates to the field of microelectronic packaging technology, and specifically discloses a preparation method of a cantilevered embedded microchannel printed circuit board. The printed circuit board includes an upper wiring layer, a metal core embedded with a microchannel, and a lower wiring layer which are sequentially stacked; the metal core includes a core body located between the upper wiring layer and the lower wiring layer and connected to the upper wiring layer and the lower wiring layer respectively, and a cantilever integrally formed with the core body; the microchannel is arranged in the core body, and the cantilever is provided with a liquid inlet and a liquid outlet communicated with the microchannel; and a preparation method of the printed circuit board is also disclosed. The printed circuit board of the present invention has both high-density integration and high-efficiency heat dissipation capabilities, and its structure and surface coating meet the requirements of airtight welding with a metal box body; the preparation method of the present invention can prevent the pollution of the printed circuit board by wet solution during the preparation process of the printed circuit board.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic packaging technology, and more specifically, to a method for preparing a cantilevered embedded microchannel printed circuit board. Background Art

[0002] A printed circuit board is a commonly used interconnection substrate in an electronic system. By embedding a microchannel in the printed circuit board, the heat dissipation ability of the printed circuit board can be significantly improved.

[0003] Chinese Patent CN105188260A discloses a printed circuit board embedded microchannel liquid cooling heat exchange device, which directly integrates the microchannel in the printed circuit board to achieve efficient heat dissipation. However, the built-in microchannel of the printed circuit board proposed in this patent is jointly composed of an organic wiring layer and a metal wiring layer in the printed circuit board. When the cooling working medium is introduced into the printed circuit board, phenomena such as moisture absorption, delamination, and liquid leakage of the organic material will occur, which is not conducive to the long-term use of the circuit board.

[0004] Chinese Patent CN113056087A discloses an embedded microchannel printed circuit board, that is, a metal core board with an embedded microchannel is first prepared, and then the core board is laminated into an embedded microchannel printed circuit board. In such an embedded microchannel printed circuit board, the cooling working medium does not come into contact with the organic material, and the reliability is higher. Using such a printed circuit board as a carrier for high-density integration and combining it with a metal box body to form a high-power component with efficient heat dissipation can significantly improve the integration density of the component while achieving efficient heat dissipation.

[0005] However, when the existing embedded microchannel printed circuit board is integrally integrated with the metal box body, its structure faces new requirements: (1) The inlet / outlet of the printed circuit board needs to be located outside the metal box body to achieve physical isolation between components such as chips and the liquid cooling interface; (2) The printed circuit board can be hermetically welded to the metal box body.

[0006] Ordinary embedded microchannel printed circuit boards cannot meet the above requirements, and it is necessary to manufacture a cantilevered embedded microchannel printed circuit board and optimize its manufacturing process to meet the integration requirements of high-power components. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a cantilevered embedded microchannel printed circuit board, which has both high-density integration and efficient heat dissipation capabilities, and its structure and surface plating meet the requirements of hermetic welding with the metal box body; at the same time, a preparation method thereof is provided, which can prevent the pollution of the printed circuit board by wet solutions during the preparation process of the printed circuit board.

[0008] The solution adopted by the present invention to solve the technical problem is:

[0009] On the one hand:

[0010] A cantilever - type embedded micro - channel printed circuit board, comprising an upper wiring layer, a metal core with an embedded micro - channel, and a lower wiring layer which are sequentially stacked;

[0011] The metal core includes a core body located between the upper wiring layer and the lower wiring layer and connected to the upper wiring layer and the lower wiring layer respectively, and a cantilever integrally formed with the core body;

[0012] The micro - channel is arranged in the core body, and the cantilever is respectively provided with a liquid inlet and a liquid outlet communicated with the micro - channel.

[0013] In some possible implementation manners, the metal core includes two stacked metal core plates; the micro - channel, the liquid inlet, and the liquid outlet are respectively arranged on one of the metal core plates.

[0014] In some possible implementation manners, the micro - channel includes a liquid inlet channel communicated with the liquid inlet, a liquid outlet channel communicated with the liquid outlet, and a heat - dissipation channel respectively communicated with the liquid inlet channel and the liquid outlet channel.

[0015] In some possible implementation manners, the printed circuit board is formed by laminating and pressing the upper wiring layer, the metal core with an embedded micro - channel, and the lower wiring layer through a prepreg; the upper wiring layer and the lower wiring layer are formed by laminating and pressing an organic wiring layer and a metal wiring layer arranged at intervals through a prepreg.

[0016] In some possible implementation manners, the side wall of the cantilever is in an arc - shaped structure, and a plating layer is arranged on the surface of the cantilever, and the plating layer is a nickel - gold plating layer or a nickel - palladium - gold plating layer.

[0017] In some possible implementation manners, the metal core is made of copper, aluminum, or molybdenum - copper alloy.

[0018] On the other hand,

[0019] The present invention discloses a preparation method of a cantilever - type embedded micro - channel printed circuit board, which specifically includes the following steps:

[0020] Step S1: Manufacturing a metal core with an embedded micro - channel, and processing a liquid inlet and a liquid outlet;

[0021] Step S2: Using a protective plug to block the liquid inlet and the liquid outlet, and treating the surface of the metal core;

[0022] Step S3: Removing the protective plug, using a gasket to seal the surfaces of the liquid inlet and the liquid outlet, and laminating and pressing the upper wiring layer, the metal core, and the lower wiring layer through a prepreg to form an embedded micro - channel printed circuit board;

[0023] Step S4: Remove the upper and lower wiring layers in the cantilever area, and at the same time retain the lower wiring layer corresponding to the positions of the liquid inlet and the liquid outlet to form an island-type fixed structure;

[0024] Step S5: Use an arc milling cutter and a wet etching process to process the side wall of the cantilever into an arc structure;

[0025] Step S6: Perform surface plating treatment on the cantilever area so that the surface coating meets the requirements for airtight welding with the metal box body;

[0026] Step S7: Process the surface structure of the cantilever to remove the island-type fixed structure and the gasket;

[0027] Step S8: Perform contour milling to complete the processing.

[0028] In some possible implementation manners, step S1 specifically includes the following steps:

[0029] Step S11: Process a microchannel above one of the metal core plates, and process a liquid inlet and a liquid outlet below the metal core plate at a position corresponding to the cantilever;

[0030] Step S12: Weld the two metal core plates to obtain a metal core with an embedded microchannel;

[0031] Step S13: Use the liquid inlet and the liquid outlet on the surface of the metal core with the embedded microchannel as the alignment reference to set the expansion and contraction ratios of each layer in the printed circuit board with the embedded microchannel.

[0032] In some possible implementation manners, step S4 specifically includes the following steps:

[0033] Adopt a depth-controlled milling process to remove the organic wiring layer, the metal wiring layer and the prepreg corresponding to the cantilever area, and retain the island-type fixed structure at the positions corresponding to the liquid inlet and the liquid outlet.

[0034] In some possible implementation manners, step S5 specifically includes the following steps:

[0035] Step S51: Use an arc milling cutter and adopt a double-sided milling process to remove the side wall metal in the cantilever area of the printed circuit board with the embedded microchannel to obtain a discontinuous arc structure;

[0036] Step S52: Use a wet etching process to etch the discontinuous arc structure into an arc structure.

[0037] Compared with the prior art, the beneficial effects of the present invention:

[0038] By adopting a cantilever, the present invention physically separates the liquid inlet / outlet of the printed circuit board from the area of components such as integrated chips in the printed circuit board, facilitating the subsequent packaging process;

[0039] By optimizing the processing process of the position of the cantilever in the printed circuit board with embedded microchannels, and adopting a process of combining an arc milling cutter with wet etching, a cantilever with an arc-shaped structure on the side is obtained, enabling the printed circuit board to meet the requirements of subsequent airtight welding with a metal box body;

[0040] By processing the liquid inlet, liquid outlet, and microchannels on the same metal core board, the present invention effectively avoids the technical problem of inaccurate relative positions of the liquid inlet, liquid outlet, and microchannels caused by dimensional expansion and contraction during the welding process of two metal core boards; using the liquid inlet and liquid outlet as the alignment reference during the lamination process of the upper wiring layer, the metal core with embedded microchannels, and the lower wiring layer can prevent problems such as misalignment caused by dimensional expansion and contraction of the metal core with embedded microchannels, the upper wiring layer, and the lower wiring layer during the lamination process;

[0041] By adopting a protective plug to protect the liquid inlet and liquid outlet through plug holes, the present invention avoids the contamination of the flow channel by the wet solution during the processing process and the blockage of the flow channel that may be caused by impurity particles in the wet solution;

[0042] By setting gaskets to protect the liquid inlet and liquid outlet, and combining the method of fixing the gaskets with "organic wiring layer, metal wiring layer, and prepreg", the present invention prevents the blockage of the flow channel caused by the prepreg material flowing into the liquid inlet and liquid outlet during the lamination process of the printed circuit board;

[0043] By adopting an island-type fixing structure, the present invention facilitates the surface plating of the non-fixed area at the cantilever, enabling the surface plating of the cantilever-type printed circuit board with embedded microchannels to meet the requirements of its airtight welding with a metal box body. Description of the Drawings

[0044] Figure 1 It is a schematic diagram of the cantilever-type printed circuit board with embedded microchannels in the present invention;

[0045] Figure 2 It is a schematic diagram of the position of the upper wiring layer and the cantilever in the present invention;

[0046] Figure 3 It is a schematic diagram of the structural layout of the microchannel, liquid inlet, liquid outlet, and cantilever in the present invention;

[0047] Figure 4 It is a schematic diagram of the cross-sectional structure of the cantilever in the present invention;

[0048] Figure 5 It is a schematic diagram of the positional relationship between the island-type fixing structure, gasket, and cantilever in the present invention;

[0049] Figure 6 Schematic diagrams of the island - type fixed structure, gasket and cantilever cross - section structure in the present invention;

[0050] Figure 7 Flow chart of the preparation method of the present invention;

[0051] Wherein: 1. Printed circuit board; 2. Metal core; 3. Liquid interface; 31. Liquid inlet; 32. Liquid outlet; 4. Organic wiring layer; 5. Metal wiring layer; 6. Prepreg; 7. Micro - channel; 8. Cantilever; 9. Liquid inlet channel; 10. Liquid outlet channel; 11. Heat dissipation channel; 12. Arc structure; 13. Island - type fixed structure; 14. Gasket; 15. Upper wiring layer; 16. Lower wiring layer; 17. Core body. Detailed implementation manners

[0052] In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integral; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. The "first", "second" and similar terms mentioned in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, terms such as "a" or "one" do not indicate a quantity limitation, but indicate that there is at least one. In the implementation of this application, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In the description of the embodiments of this application, unless otherwise stated, the meaning of "a plurality" refers to two or more. For example, a plurality of positioning posts means two or more positioning posts. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0053] The present invention will be described in detail below.

[0054] Embodiment 1:

[0055] As Figures 1-6 shown, this embodiment discloses a printed circuit board 1 with a cantilever - type embedded micro - channel 7, which includes an upper wiring layer 15, a metal core 2 embedded with a micro - channel 7 and provided with a liquid interface 3, and a lower wiring layer 16 that are sequentially stacked; wherein, the liquid interface 3 is in communication with the micro - channel 7;

[0056] The metal core 2 includes a core body 17 located between the upper wiring layer 15 and the lower wiring layer 16 and connected to the upper wiring layer 15 and the lower wiring layer 16 respectively, and cantilevers 8 integrally formed with the core body 17 respectively;

[0057] The microchannel 7 is arranged inside the core body 17, and the liquid interface 3 includes a liquid inlet 31 and a liquid outlet 32 that are respectively communicated with the microchannel 7; the liquid inlet 31 and the liquid outlet 32 are arranged on the cantilever 8.

[0058] The cantilever 8 in the present invention can be one group or multiple groups;

[0059] When it is one group, the liquid inlet 31 and the liquid outlet 32 will be arranged on this cantilever simultaneously;

[0060] When it is multiple groups, a part of them is used to arrange the liquid inlet 31, and the rest can be used to arrange the liquid outlet 32, and it is ensured that they are communicated with the microchannel 7.

[0061] In some possible implementation manners, the metal core 2 includes two metal core plates arranged in a stacked manner; the two metal core plates are specifically a metal core plate one and a metal core plate two;

[0062] Specifically, the metal core plate two is located between the metal core plate one and the upper wiring layer 15, and the microchannel 7, the liquid inlet 31, and the liquid outlet 32 are respectively arranged on the metal core plate one.

[0063] The printed circuit board 1 is formed by laminating and pressing an upper wiring layer 15, a metal core 2 with an embedded microchannel, and a lower wiring layer 16 through a semi-cured sheet 6; the upper wiring layer 15 and the lower wiring layer 16 are formed by laminating and pressing an organic wiring layer 4 and a metal wiring layer 5 that are arranged at intervals through a semi-cured sheet 6.

[0064] The metal core 2 with an embedded microchannel is made of copper, aluminum or molybdenum copper alloy.

[0065] In some possible implementation manners, in order to effectively enable the present invention to have good heat dissipation performance;

[0066] The microchannel 7 includes an inlet flow channel 9 communicated with the liquid inlet 31, an outlet flow channel 10 communicated with the liquid outlet 32, and a heat dissipation flow channel 11 respectively communicated with the inlet flow channel 9 and the outlet flow channel 10.

[0067] In some possible implementation manners, the side wall of the cantilever 8 has an arc-shaped structure 12, and a plating layer is arranged on the surface of the cantilever 8, and the plating layer is a nickel-gold plating layer or a nickel-palladium-gold plating layer.

[0068] As Figure 4 shown, by setting the side wall of the cantilever 8 as the arc-shaped structure 12 and arranging a plating layer on its surface, the requirements for airtight welding during assembly with the metal box body are met.

[0069] The present invention is provided with a cantilever 8, and the liquid inlet 31 and the liquid outlet 32 are respectively arranged on two groups of cantilevers 8. By adopting this arrangement, it is physically separated from the area of components such as integrated chips in the printed circuit board 1, facilitating the subsequent packaging process, and at the same time enabling the printed circuit board 1 to have high-density integration and efficient heat dissipation capabilities.

[0070] After the assembly of the present invention, the cantilever 8, and the liquid inlet 31 and the liquid outlet 32 arranged on the cantilever 8 will be located outside the metal box body, realizing the physical isolation between the components and the liquid cooling interfaces (liquid inlet 31, liquid outlet 32); at the same time, the printed circuit board 1 can be effectively hermetically welded to the metal box body.

[0071] Embodiment 2:

[0072] As Figure 7 shown, this embodiment specifically discloses a preparation method of a printed circuit board 1 with a cantilever-type embedded microchannel 7, which specifically includes the following steps:

[0073] Step S1: Manufacturing the metal core 2 of the embedded microchannel 7, and processing the liquid inlet 31 and the liquid outlet 32;

[0074] The step S1 specifically includes the following steps:

[0075] Step S11; Processing the microchannel 7 above one of the metal core plates, and processing the liquid inlet 31 and the liquid outlet 32 below the metal core plate at the position corresponding to the cantilever 8;

[0076] Preferably, the processing of the microchannel 7 can be realized by methods such as precision machining, chemical etching, electrical discharge machining, metal microelectroforming or laser processing;

[0077] Step S12: Welding the two metal core plates to obtain the metal core 2 with the embedded microchannel 7; specifically, it means: using methods such as vacuum diffusion welding, vacuum brazing or solder welding to weld the two metal core plates;

[0078] Preferably, by first processing the microchannel 7 and the inlet / outlet in one of the metal core plates and then welding the two metal core plates, the manufacturing of the metal core 2 is realized, avoiding the technical problem of inaccurate relative positions between the inlet / outlet and the microchannel caused by dimensional tolerances during the alignment process of the two metal core plates and dimensional expansion and contraction during the metal welding process;

[0079] Step S13: Using the liquid inlet 31 and the liquid outlet 32 on the surface of the metal core 2 as the alignment reference, setting the expansion and contraction ratios of each layer in the printed circuit board 1; specifically, according to the relative position relationship between the liquid inlet 31, the liquid outlet 32 and the metal core plate, calculating the expansion and contraction ratios of the metal core 2 in the design and production, and correspondingly adjusting the expansion and contraction ratios of other layers, so as to control the alignment accuracy between the wiring layer and the embedded microchannel metal core.

[0080] Step S2: Use a protective plug to block the liquid inlet 31 and the liquid outlet 32, and perform surface treatment on the metal core 2;

[0081] Preferably, the protective plug is a rubber plug. The method of using a rubber plug to plug the holes of the liquid inlet 31 and the liquid outlet 32 avoids the pollution of the microchannel 7 by the wet solution during the processing of the printed circuit board 1 and the blockage of the flow channel that may be caused by the impurity particles in the wet solution.

[0082] Step S3: Remove the protective plug, use a gasket 14 to seal the surfaces of the liquid inlet 31 and the liquid outlet 32, and press the upper wiring layer 15, the metal core 2 with the embedded microchannel, and the lower wiring layer 16 through the prepreg 6 to form a printed circuit board with an embedded microchannel;

[0083] By inserting the gasket 14 to protect the liquid inlet 31 and the liquid outlet 32, and combining the method of fixing the gasket 14 with the "organic wiring layer 4, metal wiring layer 5 and prepreg 6", the blockage of the flow channel caused by the inflow of the prepreg 6 material into the liquid inlet 31 and the liquid outlet 32 during the lamination process is prevented;

[0084] Step S4: Remove the upper wiring layer 15 and the lower wiring layer 16 in the cantilever 8 area, and at the same time retain the lower wiring layer 16 corresponding to the positions of the liquid inlet 31 and the liquid outlet 32 to form an island - type fixed structure 13;

[0085] Preferably, adopt a depth - controlled milling process to remove the upper wiring layer 15 and the lower wiring layer 16 corresponding to the cantilever 8 area, and retain the island - type fixed structure 13 at the positions corresponding to the liquid inlet 31 and the liquid outlet 32.

[0086] Step S5: Use an arc - shaped milling cutter for milling and a wet etching process to process the side wall of the cantilever 8 into an arc - shaped structure 12;

[0087] The said Step S5 specifically includes the following steps:

[0088] Step S51: Use an arc - shaped milling cutter and adopt a double - sided milling process to remove the side - wall metal in the cantilever area of the printed circuit board with an embedded microchannel to obtain a discontinuous arc - shaped structure;

[0089] Step S52: Use a wet etching process to etch the discontinuous arc - shaped structure into an arc - shaped structure 12.

[0090] Step S6: Perform surface plating treatment on the cantilever 8 area so that the surface coating meets the requirements for airtight welding with the metal box body;

[0091] Step S7: Process the surface structure of the cantilever 8, and remove the island - type fixed structure 13 and the gasket 14;

[0092] Step S8: Perform contour milling to complete the processing.

[0093] In this embodiment, by optimizing the processing process of the position of the cantilever 8 in the embedded microchannel printed circuit board and adopting the process of combining an arc milling cutter with wet etching, a cantilever 8 with an arc-shaped side wall structure 12 is obtained, so that the printed circuit board meets the requirements of subsequent airtight welding with the metal box body;

[0094] In this embodiment, by processing the liquid inlet 31, the liquid outlet 32 and the microchannel 7 on the same metal core board, the technical problem that the relative positions of the liquid inlet 31, the liquid outlet 32 and the microchannel 7 are inaccurate due to the dimensional expansion and contraction during the welding process of two metal core boards is effectively avoided; using the liquid inlet 31 and the liquid outlet 32 as the alignment reference during the lamination process of the upper wiring layer 15, the metal core 2 with the embedded microchannel 7 and the lower wiring layer 16 can prevent problems such as misalignment caused by dimensional expansion and contraction of the metal core 2, the upper wiring layer 15 and the lower wiring layer 16 during the lamination process;

[0095] In this embodiment, by using a protective plug to plug and protect the liquid inlet 31 and the liquid outlet 32, the pollution of the wet solution to the microchannel during the processing process and the blockage of the microchannel caused by impurity particles in the wet solution are avoided;

[0096] In this embodiment, by providing a gasket 14 to protect the liquid inlet 31 and the liquid outlet 32 and combining the method of fixing the gasket 14 with the "organic wiring layer 4, metal wiring layer 5 and prepreg 6", the blockage of the microchannel caused by the prepreg 6 material flowing into the liquid inlet 31 and the liquid outlet 32 during the lamination process of the printed circuit board is prevented;

[0097] In this embodiment, through the island-type fixing structure 13, it is convenient to electroplate the surface of the non-fixed area at the cantilever 8, so that the surface plating of the printed circuit board 1 meets the requirements of its airtight welding with the metal box body.

[0098] The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new feature or any new combination disclosed in this specification, as well as any new method or process step or any new combination disclosed.

Claims

1. A preparation method of a cantilever embedded microchannel printed circuit board, characterized in that, The cantilever - type embedded micro - channel printed circuit board includes an upper wiring layer, a metal core with an embedded micro - channel, and a lower wiring layer which are stacked in sequence; The metal core includes a core body located between the upper wiring layer and the lower wiring layer and connected to the upper wiring layer and the lower wiring layer respectively, and a cantilever integrally formed with the core body; The micro - channel is arranged in the core body, and the cantilever is respectively provided with a liquid inlet and a liquid outlet communicated with the micro - channel; specifically, it includes the following steps: Step S1: Manufacture the metal core with an embedded micro - channel, and process the liquid inlet and the liquid outlet; Step S2: Use a protective plug to block the liquid inlet and the liquid outlet, and treat the surface of the metal core; Step S3: Remove the protective plug, use a gasket to seal the surfaces of the liquid inlet and the liquid outlet, and press - laminate the upper wiring layer, the metal core, and the lower wiring layer through a prepreg to form an embedded micro - channel printed circuit board; Step S4: Remove the upper wiring layer and the lower wiring layer in the cantilever area, and at the same time retain the lower wiring layer corresponding to the positions of the liquid inlet and the liquid outlet to form an island - type fixed structure; Step S5: Use an arc - shaped milling cutter and a wet etching process to process the side wall of the cantilever into an arc - shaped structure; Step S6: Perform surface plating treatment on the cantilever area so that the surface plating meets the requirements of airtight welding with the metal box body; Step S7: Process the surface structure of the cantilever, and remove the island - type fixed structure and the gasket; Step S8: Perform contour milling to complete the processing.

2. The preparation method of a cantilever type embedded microchannel printed circuit board according to claim 1, characterized in that, The metal core includes two stacked metal core plates; the micro - channel, the liquid inlet, and the liquid outlet are respectively arranged on one of the metal core plates.

3. The preparation method of a cantilever embedded microchannel printed circuit board according to claim 1, characterized in that, The micro - channel includes a liquid inlet channel communicated with the liquid inlet, a liquid outlet channel communicated with the liquid outlet, and a heat - dissipation channel respectively communicated with the liquid inlet channel and the liquid outlet channel.

4. The preparation method of a cantilever type embedded microchannel printed circuit board according to claim 1, characterized in that, The printed circuit board is formed by press - laminating the upper wiring layer, the metal core with an embedded micro - channel, and the lower wiring layer through a prepreg; the upper wiring layer and the lower wiring layer are formed by press - laminating the organic wiring layer and the metal wiring layer arranged at intervals in a stacked manner through a prepreg.

5. The preparation method of a cantilever type embedded microchannel printed circuit board according to claim 1, characterized in that, The side wall of the cantilever is in an arc - shaped structure, and the surface of the cantilever is provided with a plating layer, and the plating layer is a nickel - gold plating layer or a nickel - palladium - gold plating layer.

6. The preparation method of a cantilevered embedded microchannel printed circuit board according to claim 2, characterized in that, The specific steps of Step S1 include the following steps: Step S11: Process the micro - channel above one of the metal core plates, and process the liquid inlet and the liquid outlet at the position corresponding to the cantilever below the metal core plate; Step S12: Weld the two metal core plates to obtain the metal core with an embedded micro - channel; Step S13: Use the liquid inlet and the liquid outlet on the surface of the metal core with an embedded micro - channel as the alignment reference to set the shrinkage and expansion ratios of each layer in the embedded micro - channel printed circuit board.

7. The preparation method of a cantilever - type embedded micro - channel printed circuit board according to claim 4, characterized in that, The specific steps of Step S4 include the following steps: Adopt a depth - controlled milling process to remove the organic wiring layer, the metal wiring layer, and the prepreg corresponding to the cantilever area, and retain the island - type fixed structure at the positions corresponding to the liquid inlet and the liquid outlet.

8. The manufacturing method of a cantilever embedded microchannel printed circuit board according to claim 7, characterized in that The specific steps of Step S5 include the following steps: Step S51: Use an arc - shaped milling cutter and adopt a double - sided milling process to remove the side - wall metal in the cantilever area of the embedded micro - channel printed circuit board to obtain a discontinuous arc - shaped structure; Step S52: Use a wet etching process to etch the discontinuous arc - shaped structure into an arc - shaped structure.

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