Circuit board and preparation method thereof
By setting up thermal blocks, holes, and divert layers in the circuit board, the heat dissipation problem of circuit boards in high -frequency high -power environments is solved, and more efficient heat dissipates.
Patent Information
- Application Number
- CN202310937250.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-27
- Publication Date
- 2025-01-28
AI Technical Summary
In high-frequency and high-power working environments, the internal loss of the circuit board is large and the heat generated is high. The heat dissipation effect of existing copper blocks is poor and needs to be improved.
Design a circuit board, including the first line substrate, the first heating block, the second line substrate, and the core board. The first heating block is located in the first groove. The connection, the heat dissipation area of the heat guide block is added.
By passing the heat to the hole, the external airflow spreads heat, which improves the heat dissipation effect and efficiency.
Smart Images
Figure CN119383823A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to circuit board production, and in particular to a circuit board and a method for preparing the same. Background Art
[0002] With the development of 5G technology, printed circuit boards (PCBs) are also gradually developing towards high-frequency and high-speed functions. PCBs have large internal losses and generate high heat in high-frequency and high-power working environments. In order to solve the heat dissipation problem of PCBs, copper blocks are usually embedded in the circuit board. However, the heat dissipation effect of the copper blocks is not good and needs to be improved. Summary of the invention
[0003] In view of this, the present application provides a circuit board and a method for manufacturing the same to solve the above problems.
[0004] The present application provides a circuit board, including a first circuit substrate, a first heat-conducting block, a second circuit substrate and a core board. The first circuit substrate includes a first circuit layer and a first dielectric layer stacked in a first direction, the first circuit substrate is provided with two first grooves spaced apart in a second direction, the first grooves are at least provided in the first dielectric layer, and the second direction is perpendicular to the first direction; a first heat-conducting block is located in each of the first grooves; the core board is located between the first circuit substrate and the second circuit substrate in the first direction; the circuit board is provided with a through hole, the through hole passes through the first circuit substrate, the core board and the second circuit substrate, the through hole is provided between the two first heat-conducting blocks in the second direction, the first heat-conducting block forms part of the inner wall of the through hole, a conductive layer is provided on the inner wall of the through hole, and the conductive layer is connected to the first heat-conducting block.
[0005] In some embodiments, the second circuit substrate includes a second circuit layer and a second dielectric layer stacked in the first direction, the second circuit substrate is provided with two second grooves spaced apart in the second direction, the circuit board also includes a second heat conductive block, the second heat conductive block is located in each of the second grooves, the second heat conductive block forms a portion of the inner wall of the through hole, and the conductive layer is connected to the second heat conductive block.
[0006] In some embodiments, in the first direction, the first heat conductive block overlaps with the second heat conductive block.
[0007] In some embodiments, the first groove penetrates the first circuit layer and the first dielectric layer in the first direction, and the first heat conductive block is connected to the core board.
[0008] In some embodiments, when viewed from the first direction, the through hole is circular.
[0009] The present application also provides a method for preparing a circuit board, comprising: providing a substrate unit, the substrate unit comprising a first substrate, a core board and a second substrate stacked in a first direction; opening two first grooves spaced apart in a second direction on the first substrate, the second direction being perpendicular to the first direction; filling a first heat-conducting block in each of the first grooves; opening a through hole penetrating the first substrate, the core board and the second substrate along the first direction, the through hole being arranged between two of the first heat-conducting blocks in the second direction, the first heat-conducting block forming part of the inner wall of the through hole; forming a conductive layer on the inner wall of the through hole, the conductive layer connecting the first heat-conducting blocks to obtain the circuit board.
[0010] In some embodiments, before opening the through hole, the preparation method also includes: opening two second grooves spaced apart in the second direction on the second substrate; filling a second thermally conductive block in each of the second grooves, the through hole being arranged between the two second thermally conductive blocks in the second direction, and the second thermally conductive block forming a portion of the inner wall of the through hole.
[0011] In some embodiments, forming the first groove specifically includes: covering the first substrate with a dry film, the first substrate including a first conductive layer and a first dielectric layer stacked in the first direction, the dry film having a window for exposing a portion of the first conductive layer; forming a first opening in the first conductive layer exposed at the window by exposure and development, the first opening being used to expose a portion of the first dielectric layer; and obtaining the first groove by laser etching the first dielectric layer exposed at the first opening.
[0012] In some embodiments, after forming the conductive layer, the preparation method further comprises: etching the first conductive layer by exposure and development to obtain a first circuit layer.
[0013] In some embodiments, the first heat conductive block is formed in the first groove by electroplating.
[0014] In the present application, a first heat-conducting block, a through hole and a conducting layer are arranged in the circuit board, the first heat-conducting block and the conducting layer are connected and attached, the heat of the first heat-conducting block can be directly transferred to the through hole through the conducting layer, the through hole passes through the first circuit substrate, the core board and the second circuit substrate, the external airflow can pass through the through hole and dissipate the heat transferred to the through hole, thereby improving the heat dissipation effect. In the present application, the conducting layer directly receives the heat of the first heat-conducting block, and the conducting layer has a certain thickness, which relatively increases the heat dissipation area of the first heat-conducting block and improves the heat dissipation efficiency; at the same time, the first heat-conducting blocks located on both sides of the through hole are embedded in the first groove and connected through the conducting layer. The addition of heat-conducting blocks can not only improve the heat dissipation of the circuit board, but also the first heat-conducting blocks located on both sides of the through hole can also transfer heat through the conducting layer and dissipate heat through the through hole to improve the heat dissipation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 A top view of the circuit board provided for this application.
[0016] Figure 2 For Figure 1 The cross-sectional view of the circuit board along II-II in one embodiment is shown.
[0017] Figure 3 For Figure 1 A schematic cross-sectional view of a circuit board along line II-II in another embodiment is shown.
[0018] Figure 4 A schematic cross-sectional view of the substrate provided in this application.
[0019] Figure 5 for Figure 4 The cross-sectional schematic diagram of the substrate shown is covered with dry films on both sides.
[0020] Figure 6 for Figure 5 The schematic cross-sectional view of a first opening and a second opening formed on a substrate is shown.
[0021] Figure 7 for Figure 6 The schematic cross-sectional view shows a first groove and a second groove formed on a substrate.
[0022] Figure 8 for Figure 7 The schematic cross-sectional view of the substrate after the first heat-conducting block and the second heat-conducting block are filled is shown.
[0023] Fig. 9 for Figure 8 The cross-sectional schematic diagram of a substrate having a through hole is shown.
[0024] Fig.10 for Fig. 9The schematic cross-sectional view of the conductive layer formed on the inner wall of the through hole of the substrate is shown.
[0025] Main component symbols
[0026] Circuit board 100
[0027] First circuit substrate 10
[0028] The first circuit layer 11
[0029] The first dielectric layer 12
[0030] Core plate 20, 20a
[0031] The third circuit layer 21
[0032] The third dielectric layer 22
[0033] Second circuit substrate 30
[0034] The second circuit layer 31
[0035] The second dielectric layer 32
[0036] The first heat conducting block 41
[0037] The second heat conducting block 42
[0038] Through hole 50
[0039] Conductive layer 60
[0040] Protective layer 70
[0041] Base unit 1000
[0042] First substrate 101
[0043] The first conductive layer 1011
[0044] First opening 1012
[0045] First groove 1013
[0046] Dry film 201
[0047] Second substrate 301
[0048] The second conductive layer 3011
[0049] Second opening 3012
[0050] Second groove 3013
[0051] First direction X
[0052] Second direction Y DETAILED DESCRIPTION
[0053] The embodiments of the present invention are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.
[0055] The specific implementation methods of the present application are further described in detail below with reference to the accompanying drawings.
[0056] See also Figure 1 and Figure 2 The embodiment of the present application provides a circuit board 100, including a first circuit substrate 10, a core board 20, a second circuit substrate 30, a first heat conducting block 41 and a conductive layer 60. The first circuit substrate 10 includes a first circuit layer 11 and a first dielectric layer 12 stacked in a first direction X. Two first grooves 1013 arranged at intervals in a second direction Y are provided in the first circuit substrate 10, and the first grooves 1013 are at least provided in the first dielectric layer 12, and the second direction Y is perpendicular to the first direction X. The core board 20 is located between the first circuit substrate 10 and the second circuit substrate 30 in the first direction X. The first heat conducting block 41 is located in each first groove 1013. The second circuit substrate 30 includes a second circuit layer 31 and a second dielectric layer 32 stacked. The circuit board 100 is provided with a through hole 50. The through hole 50 passes through the first circuit substrate 10, the core board 20 and the second circuit substrate 30. The through hole 50 is provided between the two first heat conducting blocks 41 in the second direction Y, and the first heat conducting block 41 forms part of the inner wall of the through hole 50. A conducting layer 60 is disposed on the inner wall of the through hole 50 , and the conducting layer 60 is connected to the first heat conducting block 41 .
[0057] In the above scheme, by setting the first heat-conducting block 41, the through hole 50 and the conductive layer 60 in the circuit board 100, the first heat-conducting block 41 and the conductive layer 60 are connected and attached, and the heat of the first heat-conducting block 41 can be directly transferred to the through hole 50 through the conductive layer 60. The through hole 50 passes through the first circuit substrate 10, the core board 20 and the second circuit substrate 30. The external airflow can pass through the through hole 50 and dissipate the heat transferred to the through hole 50, thereby improving the heat dissipation effect. In the present application, the conductive layer 60 directly receives the heat of the first heat-conducting block 41, and the conductive layer 60 has a certain thickness, which relatively increases the heat dissipation area of the first heat-conducting block 41 and improves the heat dissipation efficiency. At the same time, the first heat-conducting blocks 41 located on both sides of the through hole 50 are embedded in the first groove 1013 and connected through the conductive layer 60. The additional heat-conducting blocks can not only improve the heat dissipation of the circuit board 100, but also the first heat-conducting blocks 41 located on both sides of the through hole 50 can transfer heat through the conductive layer 60 and dissipate heat through the through hole 50 to improve the heat dissipation efficiency.
[0058] In some embodiments, the material of the dielectric layer is an insulating resin. Specifically, the material of the dielectric layer can be selected from one of resins such as epoxy resin, polypropylene (PP), BT resin, polyphenylene oxide (PPO), polypropylene (PP), polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).
[0059] In some embodiments, the core board 20 may include a circuit layer, or multiple circuit layers and dielectric layers, or glue layers. Figure 2 In this embodiment, the core board 20 may include two third circuit layers 21 and a third dielectric layer 22 disposed between the two third circuit layers 21, and the two third circuit layers 21 are respectively connected to the first circuit substrate 10 and the second circuit substrate 30. In other embodiments, the number of third circuit layers 21 in the core board 20a may be changed according to actual needs.
[0060] See also Figure 2 In this embodiment, the first dielectric layer 12 and the second dielectric layer 32 are respectively disposed on two surfaces of the core board 20 .
[0061] See also Figure 2 In some embodiments, the conductive layer 60 can be used to electrically connect the first circuit substrate 10 and the second circuit substrate 30, and can also be used to achieve heat transfer to the first heat conducting block 41. In some embodiments, the conductive layer 60 is formed on the inner wall of the through hole 50 by electroplating.
[0062] See also Figure 2 In some embodiments, the second circuit substrate 30 is provided with two second grooves 3013 spaced apart in the second direction Y, and the circuit board 100 further includes a second heat-conducting block 42, the second heat-conducting block 42 is located in each second groove 3013, the second heat-conducting block 42 forms a part of the inner wall of the through hole 50, and the conductive layer 60 is connected to the second heat-conducting block 42. The first heat-conducting block 41 and the second heat-conducting block 42 are respectively arranged on both sides of the core board 20 to increase the heat dissipation area of the circuit board 100 and improve the heat dissipation of the circuit board 100. Both the first heat-conducting block 41 and the second heat-conducting block 42 are connected to the conductive layer 60, and both the first heat-conducting block 41 and the second heat-conducting block 42 can directly transfer heat to the through hole 50 through the conductive layer 60 and be carried away by the airflow, and the first heat-conducting block 41 and the second heat-conducting block 42 can also transfer heat through the conductive layer 60, thereby accelerating the heat dissipation efficiency to a certain extent and improving the heat dissipation capacity.
[0063] In some embodiments, the first heat conducting block 41 is formed in the first circuit substrate 10 by electroplating, and the second heat conducting block 42 is formed in the second circuit substrate 30 by electroplating. Compared with the technical solution of burying copper in the circuit board 100 in the prior art, the present application forms the corresponding first heat conducting block 41 and second heat conducting block 42 by electroplating in the first circuit substrate 10 and the second circuit substrate 30 by electroplating process, which can save the glue (such as PP glue) used to connect the copper blocks to bury the circuit board 100, and can also avoid the problem of residual glue generated in the process of connecting with glue and the increase of the expansion and contraction coefficient of the circuit board 100 after brushing the board surface of the circuit board 100 to remove the residual glue.
[0064] In some embodiments, in the first direction X, the first heat conductive block 41 and the second heat conductive block 42 overlap. Such an arrangement in the stacking direction of the circuit board 100 can shorten the distance between the first heat conductive block 41 and the second heat conductive block 42, so that rapid heat transfer can be achieved between the first heat conductive block 41 and the second heat conductive block 42 via the conductive layer 60.
[0065] In some embodiments, the first groove 1013 penetrates the first circuit layer 11 and the first dielectric layer 12 in the first direction X, and the first heat conductive block 41 is connected to the core board 20. The first heat conductive block 41 is embedded in the first dielectric layer 12 and extends to the first circuit layer 11. This arrangement is to further increase the size of the first heat conductive block 41 in the circuit board 100 without increasing the overall thickness of the circuit board 100, so as to increase the heat dissipation area. And when the first circuit layer 11 is the outermost circuit layer of the circuit board 100, the first heat conductive block 41 is directly exposed to the outer surface of the circuit board 100, and the efficiency of the first heat conductive block 41 transferring heat to the environment can also be increased. Similarly, the second groove 3013 penetrates the second circuit layer 31 and the second dielectric layer 32 in the first direction X, and the second heat conductive block 42 is connected to the core board 20. The second heat conductive block 42 is also embedded in the second dielectric layer 32 and extends to the second circuit layer 31, and also has the effect of the first heat conductive block 41 improving the heat dissipation of the circuit board 100.
[0066] See also Figure 2 In some embodiments, in the second direction Y, the circuit board 100 is provided with a first heat-conducting block 41 on both sides of the through hole 50. Correspondingly, the circuit board 100 is also provided with a second heat-conducting block 42 on both sides of the through hole 50, and the two second heat-conducting blocks 42 are also connected through the conductive layer 60. Compared with a single independent heat-conducting block, each heat-conducting block of the present application is connected to the conductive layer 60, and the four heat-conducting blocks can transfer heat to each other through the conductive layer 60 and dissipate heat through the through hole 50. If one or more of them generates heat, the heat can be transferred between the four heat-conducting blocks through the conductive layer 60, thereby improving the overall heat dissipation efficiency of the circuit board 100.
[0067] In some embodiments, when viewed from the first direction, the through hole 50 is circular, which is easier to drill and manufacture than other shapes.
[0068] In some embodiments, a plurality of through holes 50 may be provided between the two first heat conducting blocks 41 in the circuit board 100. In this embodiment, only two through holes 50 are used as an example. Figure 1 , but this is not a limitation.
[0069] See also Figure 2 , Figures 4 to 10 The present application also provides a method for preparing a circuit board 100, comprising the following steps:
[0070] S1.Please refer to Figure 4A substrate unit 1000 is provided, and the substrate unit 1000 includes a first substrate 101, a core board 20, and a second substrate 301 which are stacked. The first substrate 101 includes a first dielectric layer 12 and a first conductive layer 1011 which are stacked, and the second substrate 301 includes a second dielectric layer 32 and a second conductive layer 3011 which are stacked, and the core board 20 is located between the first dielectric layer 12 and the second dielectric layer 32.
[0071] The first substrate 101 , the core substrate 20 and the second substrate 301 are formed by lamination.
[0072] In this embodiment, the core board 20 may include two third circuit layers 21 and a third dielectric layer 22 disposed between the two third circuit layers 21 . The two third circuit layers 21 are connected to the first circuit substrate 10 and the second circuit substrate 30 , respectively.
[0073] S2. See Figure 5 , the dry film 201 is covered on the first conductive layer 1011 and the second conductive layer 3011 respectively, and windows are made on the dry film 201 (not shown).
[0074] Among them, the window can be made by exposure and development.
[0075] S3. See Figure 6 , a plurality of first openings 1012 and a plurality of second openings 3012 are respectively formed on the first conductive layer 1011 and the second conductive layer 3011 by opening windows.
[0076] A portion of the first dielectric layer 12 is exposed to the first opening 1012 , and a portion of the second dielectric layer 32 is exposed to the second opening 3012 .
[0077] In this embodiment, two first openings 1012 and two second openings 3012 are used as examples for description.
[0078] S4. See Figure 7 A hole is opened in the first dielectric layer 12 through the first opening 1012 to obtain two first grooves 1013 spaced apart in the second direction Y, and a hole is opened in the second dielectric layer 32 through the second opening 3012 to obtain two second grooves 3013 spaced apart in the second direction Y, and the second direction Y is perpendicular to the first direction X.
[0079] In some embodiments, a laser may be used to drill a hole in the first dielectric layer 12 through the first opening 1012, and the hole (not labeled in the figure) in the first dielectric layer 12 is connected to the first opening 1012 to form a first groove 1013. A laser may be used to drill a hole in the second dielectric layer 32 through the second opening 3012, and the hole (not labeled in the figure) in the second dielectric layer 32 is connected to the second opening 3012 to form a second groove 3013.
[0080] In some embodiments, two opposite surfaces of the core board 20 are respectively exposed to the first groove 1013 and the second groove 3013 to increase the depth of the first groove 1013 and the second groove 3013 in the thickness direction of the substrate unit 1000 (i.e., the stacking direction of the first substrate 101, the core board 20 and the second substrate 301).
[0081] S5. See Figure 8 , a first heat conducting block 41 is filled in each first groove 1013 , and a second heat conducting block 42 is filled in each second groove 3013 .
[0082] In some embodiments, two groups of first grooves 1013 are formed on the first substrate 101, and the two groups of first grooves 1013 are filled with first heat conducting blocks 41; the two groups of second grooves 3013 are filled with second heat conducting blocks 42. Along the stacking direction of the substrate in the first direction X, the two groups of first heat conducting blocks 41 are symmetrically arranged, and the two groups of second heat conducting blocks 42 are symmetrically arranged.
[0083] In some embodiments, a first heat-conducting block 41 is formed in the first groove 1013 by electroplating, and a second heat-conducting block 42 is formed in the second groove 3013 by electroplating, so that the first heat-conducting block 41 is completely filled in the first groove 1013, and the second heat-conducting block 42 is completely filled in the second groove 3013. There is no gap between the groove and the heat-conducting block, and the overall thickness of the heat-conducting block can also be made consistent, which is beneficial to the subsequent processing of the circuit board 100.
[0084] In some embodiments, the cross-sectional width of the first groove 1013 is uniform along the direction from the first substrate 101 to the core board 20. In other embodiments, the opening of the cross section of the first groove 1013 may be gradually reduced, which is more conducive to electroplating in the first groove 1013.
[0085] S6. See Fig. 9 A through hole 50 is opened along the first direction X and passes through the first substrate 101, the core board 20 and the second substrate 301. The through hole 50 is arranged between the two first heat-conducting blocks 41 in the second direction Y. The first heat-conducting block 41 and the second heat-conducting block 42 both form part of the inner wall of the through hole 50.
[0086] The through hole 50 is also provided between the two second heat-conducting blocks 42 in the second direction Y. The first heat-conducting block 41 and the second heat-conducting block 42 are both copper blocks.
[0087] S7. See Fig.10 A conducting layer 60 is formed on the inner wall of the through hole 50 , and the conducting layer 60 connects the first heat conducting block 41 and the second heat conducting block 42 .
[0088] In some embodiments, the conductive layer 60 is formed on the inner wall of the through hole 50 by electroplating. The through hole 50 and the conductive layer 60 are provided to connect the first heat conductive block 41 and the second heat conductive block 42, and the first heat conductive block 41 and the second heat conductive block 42 are heat-transferred through the conductive layer 60, which is also conducive to transferring the heat on the first heat conductive block 41 and the second heat conductive block 42 to the conductive layer 60 and dissipating it through the through hole 50. In some embodiments, the conductive layer 60 can also electrically connect the first conductive layer 1011 and the second conductive layer 3011. The conductive layer 60 is copper.
[0089] In this embodiment, the two groups of first heat-conducting blocks 41 and the two groups of second heat-conducting blocks 42 are both connected to the conducting layer 60 .
[0090] S8. See Figure 2 , the first conductive layer 1011 and the second conductive layer 3011 are etched to obtain the circuit board 100.
[0091] In some embodiments, the first conductive layer 1011 and the second conductive layer 3011 are both subjected to steps such as lamination of dry films, exposure, development, etching, and film removal to obtain the corresponding first circuit layer 11 and second circuit layer 31, respectively.
[0092] In the present application, by setting the first heat-conducting block 41, the through hole 50 and the conductive layer 60 in the circuit board 100, the first heat-conducting block 41 and the conductive layer 60 are connected and attached, and the heat of the first heat-conducting block 41 can be directly transferred to the through hole 50 through the conductive layer 60. The through hole 50 passes through the first circuit substrate 10, the core board 20 and the second circuit substrate 30. The external airflow can pass through the through hole 50 and dissipate the heat transferred to the through hole 50, thereby improving the heat dissipation effect. In the present application, the conductive layer 60 directly receives the heat of the first heat-conducting block 41, and the conductive layer 60 has a certain thickness, which relatively increases the heat dissipation area of the first heat-conducting block 41 and improves the heat dissipation efficiency. At the same time, the first heat-conducting blocks 41 located on both sides of the through hole 50 are embedded in the first groove 1013 and connected through the conductive layer 60. The additional heat-conducting blocks can not only improve the heat dissipation of the circuit board 100, but also the first heat-conducting blocks 41 located on both sides of the through hole 50 can transfer heat through the conductive layer 60 and dissipate heat through the through hole 50 to improve the heat dissipation efficiency.
[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the embodiments, a person skilled in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.
Claims
1. A circuit board, characterized in that: include: A first circuit substrate comprises a first circuit layer and a first dielectric layer stacked in a first direction, wherein the first circuit substrate is provided with two first grooves spaced apart in a second direction, wherein the first grooves are at least provided in the first dielectric layer, and the second direction is perpendicular to the first direction; A first heat conducting block, located in each of the first grooves; a second circuit substrate; as well as a core board, located between the first circuit substrate and the second circuit substrate in the first direction; The circuit board is provided with a through hole, and the through hole passes through the first circuit substrate, the core board and the second circuit substrate. The through hole is arranged between the two first thermally conductive blocks in the second direction. The first thermally conductive block forms a part of the inner wall of the through hole. A conductive layer is provided on the inner wall of the through hole, and the conductive layer is connected to the first thermally conductive block.
2. The circuit board according to claim 1, characterized in that The second circuit substrate includes a second circuit layer and a second dielectric layer stacked in the first direction, the second circuit substrate is provided with two second grooves spaced apart in the second direction, the circuit board also includes a second heat conductive block, the second heat conductive block is located in each of the second grooves, the second heat conductive block forms a portion of the inner wall of the through hole, and the conductive layer is connected to the second heat conductive block.
3. The circuit board according to claim 2, characterized in that: In the first direction, the first heat conducting block overlaps with the second heat conducting block.
4. The circuit board according to claim 1, characterized in that: The first groove penetrates the first circuit layer and the first dielectric layer in the first direction, and the first heat conductive block is connected to the core board.
5. The circuit board according to claim 1, wherein: When viewed from the first direction, the through hole is circular.
6. A method for preparing a circuit board, characterized in that: include: Providing a substrate unit, the substrate unit comprising a first substrate, a core substrate and a second substrate stacked in a first direction; Two first grooves are formed on the first substrate and are spaced apart from each other in a second direction, wherein the second direction is perpendicular to the first direction; Filling a first heat conducting block in each of the first grooves; A through hole is provided along the first direction to penetrate the first substrate, the core plate and the second substrate, the through hole is provided between two first heat-conducting blocks in the second direction, and the first heat-conducting blocks form a part of the inner wall of the through hole; A conducting layer is formed on the inner wall of the through hole, and the conducting layer is connected to the first heat conducting block to obtain the circuit board.
7. The method for preparing a circuit board according to claim 6, characterized in that: Before forming the through hole, the preparation method further comprises: Two second grooves are formed on the second substrate and are spaced apart from each other in the second direction; A second heat-conducting block is filled in each of the second grooves, the through hole is arranged between two of the second heat-conducting blocks in the second direction, and the second heat-conducting block forms a part of the inner wall of the through hole.
8. The method for preparing a circuit board according to claim 6, characterized in that: The step of forming the first groove specifically includes: Covering the first substrate with a dry film, wherein the first substrate includes a first conductive layer and a first dielectric layer stacked in the first direction, and the dry film has a window for exposing a portion of the first conductive layer; Forming a first opening in the first conductive layer exposed at the opening by exposure and development, wherein the first opening is used to expose a portion of the first dielectric layer; The first dielectric layer exposed in the first opening is etched by laser to obtain the first groove.
9. The method for preparing a circuit board according to claim 8, characterized in that: After forming the conducting layer, the preparation method further comprises: The first conductive layer is etched by exposure and development to obtain a first circuit layer.
10. The method for preparing a circuit board according to claim 6, characterized in that: The first heat conducting block is formed in the first groove by electroplating.