A circuit board and a manufacturing method thereof

Abstract

The present application discloses a circuit board and a manufacturing method thereof. The manufacturing method of the circuit board includes: preparing at least two sub-boards, each sub-board being formed by sequentially and alternately laminating at least one layer of substrate and at least two layers of conductive circuit layers, and a first conductive layer being formed on the first side of at least one sub-board; opening a first through-hole on the first side of the sub-board and electroplating to form a first conductive hole, the first conductive hole being connected to the first conductive layer, and the first conductive hole electrically connecting at least two conductive circuit layers connected thereto; laminating and fixing two sub-boards to form a mother board, wherein the first side of one sub-board is located on the side facing away from the other sub-board; forming a second through-hole on the mother board and electroplating the second conductive hole to form a second conductive hole, the second conductive hole being connected to the first conductive layer, and electrically connecting at least two specified conductive circuit layers on the mother board. Through the above solution, the signal transmission loss of the formed circuit board can be reduced.

Description

Technical Field

[0001] This application belongs to the technical field of printed circuit board processing, and particularly relates to a circuit board and a manufacturing method thereof. Background Art

[0002] In the field of PCB (Printed Circuit Boards) production, for large-capacity PCB circuit boards, generally, first conductive holes can be opened on opposite sides of the same hole position on the PCB circuit, and then second conductive holes that need to penetrate the entire circuit board are opened at other hole positions. When manufacturing existing large-capacity PCB circuit boards, it usually occurs that the conductive layers respectively connected to the first conductive hole and the second conductive hole are not at the same height, which will increase the signal transmission loss of the circuit board. Therefore, when ensuring the transmission loss of the PCB circuit board, other high-speed transmission materials need to be used, which will increase the manufacturing cost of the PCB circuit board. Summary of the Invention

[0003] This application provides a circuit board and a manufacturing method thereof to solve the above technical problems.

[0004] To solve the above technical problems, a technical solution adopted by this application is: to provide a manufacturing method of a circuit board, the manufacturing method of the circuit board includes:

[0005] Prepare at least two sub-boards, each of the sub-boards is formed by alternately laminating at least one substrate and at least two conductive circuit layers in sequence, and a first conductive layer is formed on the first side of at least one of the sub-boards;

[0006] Open a first through-hole on the first side of the sub-board and electroplate to form a first conductive hole, the first conductive hole is connected to the first conductive layer, and the first conductive hole electrically connects at least two of the conductive circuit layers it connects;

[0007] Stack and fix two of the sub-boards to form a mother board, wherein the first side of one of the sub-boards is located on the side facing away from the other sub-board;

[0008] Form a second through-hole on the mother board, and electroplate the second conductive hole to form a second conductive hole, the second conductive hole is connected to the first conductive layer, and electrically connects at least two specified conductive circuit layers on the mother board.

[0009] To solve the above technical problems, a technical solution adopted by this application is: to provide a circuit board, the circuit board includes:

[0010] Two stacked sub-boards, each of the sub-boards includes at least one substrate and at least two conductive circuit layers, and the at least one substrate and the at least two conductive circuit layers are stacked and alternately arranged;

[0011] A first conductive layer is disposed on a first side of at least one of the sub-boards, and the first side of the sub-board is on a side facing away from the other sub-board;

[0012] A first conductive hole is formed by opening a first through-hole on the first side of the sub-board and electroplating. The first conductive hole is connected to the first conductive layer, and the first conductive hole is used to electrically connect at least two specified conductive line layers on its corresponding sub-board; and

[0013] A second conductive hole is formed by forming a second through-hole on the mother board and electroplating the second conductive hole. The second conductive hole is connected to the first conductive layer, and the second conductive hole is used to electrically connect at least two specified conductive line layers of the two sub-boards.

[0014] The beneficial effects of the present application are as follows: By connecting both the first conductive hole and the second conductive hole to the first conductive layer, the technical solution of the present application can avoid the lack of electromagnetic shielding at the opening positions of the first conductive hole and the second conductive hole. Therefore, the signal transmission efficiency of the formed circuit board can be improved, and the signal transmission loss can be reduced. Further, the manufacturing process of the circuit board provided in the present application is simple, the production time can be shortened, the production efficiency can be improved, and thus the production cost can be saved. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings, where:

[0016] Figures 1a - 1c is a schematic flowchart of an embodiment of a conventional method for manufacturing a circuit board;

[0017] Figure 2 is a schematic flowchart of an embodiment of a method for manufacturing a circuit board provided by the present application;

[0018] Figures 3a - 3j is a schematic flowchart of another embodiment of a method for manufacturing a circuit board provided by the present application;

[0019] Figure 4 is a schematic structural diagram of an embodiment of a circuit board provided by the present application. Detailed Description of the Embodiments

[0020] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0021] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present application, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0022] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present application.

[0023] Please refer to Figures 1a - 1c 。 Figures 1a - 1c is a schematic flowchart of an embodiment of a method for manufacturing an existing circuit board.

[0024] As Figures 1a - 1b shown, in this step, at least two sub-boards need to be prepared, and each sub-board includes at least one layer of substrate 310 and at least two layers of conductive circuit layers 320. At least one layer of substrate 310 and at least two layers of conductive circuit layers 320 can be stacked and alternately arranged.

[0025] Among them, vias can be opened on the sub-board, and then the vias are electroplated to form an electroplated layer in the vias, and then a first conductive hole 330 can be formed. The first conductive hole 330 can be connected to the conductive circuit layer 320 on the surface side of the sub-board, and the first conductive hole 330 can electrically connect at least two layers of conductive circuit layers 320 of the sub-board.

[0026] After the first conductive hole 330 is formed, the conductive circuit layer 320 on the surface of the sub-board needs to be patterned to form a conductive circuit (or pad) 321 connected to the first conductive hole 330.

[0027] As Figure 1cAs shown, after forming the conductive line (or pad) 321 connected to the first conductive via 330 on the daughter board, the two daughter boards can be stacked and fixed to form a mother board, and then the second conductive via 360 can be formed on the mother board. Correspondingly, the formation method of the second conductive via 360 can be the same as that of the first conductive via 330. The difference is that the second conductive via 360 can penetrate through the two daughter boards in sequence, and the second conductive via 360 can electrically connect at least two specified conductive line layers 320 in the mother board. For example, the second conductive via 360 can electrically connect at least one conductive line layer 320 on each of the two daughter boards to realize signal transmission between the two daughter boards.

[0028] In this step, when forming the plating layer in the second conductive via 360, it is necessary to perform electroless copper plating, black hole or black shadow treatment on the through hole corresponding to the second conductive via 360, so as to form a conductive layer on the inner wall of the through hole. This conductive layer can be used as a seed layer, and then electroplating is performed based on this seed layer, so that the plating layer of the second conductive via 360 can be formed.

[0029] When performing electroless copper plating, black hole or black shadow treatment on the through hole corresponding to the second conductive via 360, in order to prevent the solution used in the process of electroless copper plating, black hole or black shadow treatment from entering the first conductive via 330 and causing the first conductive via 330 to be corroded and damaged, it is necessary to seal the opening of the first conductive via 330.

[0030] Generally speaking, a covering layer 350 can usually be provided on one side of the opening of the first conductive via 330 to seal the opening of the first conductive via 330. Among them, the covering layer 350 can be fixedly attached to the first conductive via 330 through a connecting layer 352 to encapsulate the opening of the first conductive via 330. The covering layer 350 can be a metal layer formed by a thin sheet such as copper foil. Then, a through hole is opened on the mother board and electroplated to form the second conductive via 360. At this time, due to the provision of the covering layer 350, the opening of the second conductive via 360 is located on the side of the covering layer 350 away from the mother board, so that the positions of the openings of the second conductive via 360 and the first conductive via 330 are not aligned. Therefore, when the first conductive via 330 and the second conductive via 360 are plugged and matched with different pins of the component and electrically connected, electromagnetic shielding loss is likely to occur at the positions of the openings of the first conductive via 330 and the second conductive via 360, which will increase the signal transmission loss of the entire circuit board.

[0031] It should be noted that if it is necessary to ensure that the second conductive hole 360 can electrically connect at least one conductive line layer 320 on each of the two sub-boards, after forming the first conductive hole 330 on the sub-board, at least two sub-boards need to be stacked to form a mother board, and then a through hole is formed in the mother board to form the second conductive hole 360. At this time, a covering layer 350 needs to be covered at the opening position of the first conductive hole 330. Therefore, the metal layers connected by the openings of the first conductive hole 330 and the second conductive hole 360 on one side of the mother board are different layers; if a conductive through hole is formed on the sub-board, and then the sub-boards are stacked to form a mother board so that the conductive through holes on different sub-boards are connected to each other to form the second conductive hole 360, this solution can make the metal layers connected by the openings of the first conductive hole 330 and the second conductive hole 360 on one side of the mother board be the same layer. However, it is difficult to ensure effective electrical connection between different conductive through holes in this solution, and electroplating needs to be performed on the formed second conductive hole 360, so the manufacturing process will be more complicated and the production efficiency will be reduced.

[0032] To solve the above technical problems, the present application provides a manufacturing method of a circuit board. Please refer to Figure 2 , Figure 2 which is a schematic flow chart of an embodiment of a manufacturing method of a circuit board provided by the present application.

[0033] The manufacturing method of the circuit board specifically includes the following steps:

[0034] S101: Prepare at least two sub-boards, each sub-board is formed by alternately laminating at least one substrate and at least two conductive line layers in sequence, and a first conductive layer is formed on the first side of at least one sub-board.

[0035] In this step, at least two sub-boards need to be prepared first. Each sub-board can be formed by alternately laminating at least one substrate and at least two conductive line layers in sequence and stacking them.

[0036] Among them, a first conductive layer is formed on the first side surface of at least one sub-board. The first conductive layer can be a metal layer on the first side surface of the sub-board, and the first conductive layer can cover at least part or all of the area of the first side surface of the sub-board. The first conductive layer can be formed into multiple conductive lines with a preset pattern after being patterned. For the subsequent processing of the first conductive layer, please refer to the following text in detail.

[0037] Among them, it should be noted that the conductive line layers on the inner layer of each sub-board can be conductive line layers with multiple conductive lines that have completed the patterning process.

[0038] In this embodiment, the substrate can be made of an insulating material. For example, the substrate can be made of a resin material. It is made by impregnating a reinforcing material with a resin adhesive and through processes such as drying, cutting, and laminating. The material of the conductive circuit layer can include, but is not limited to, materials such as copper, aluminum, iron, nickel, gold, silver, platinum group, chromium, magnesium, tungsten, molybdenum, lead, tin, indium, zinc, or their alloys.

[0039] S102: Open a first through-hole on the first side of the daughter board and electroplate to form a first conductive hole. The first conductive hole is connected to the first conductive layer, and the first conductive hole electrically connects at least two conductive circuit layers it is connected to.

[0040] In this step, a first conductive hole can be opened on the first side of the daughter board. Specifically, a first through-hole can be opened from the first side of the daughter board (the side with the first conductive layer). The first through-hole penetrates at least one substrate layer and at least two conductive circuit layers of the daughter board. By electroplating, a plating layer electrically connecting the first conductive layer can be formed on the inner wall of the first through-hole, thereby forming a first conductive hole.

[0041] Among them, the first conductive hole is connected to the first conductive layer, and the first conductive layer can electrically connect at least two conductive circuit layers it is connected to. For example, the first conductive hole can electrically connect the first conductive layer and a conductive circuit layer of any inner layer in the daughter board, or when the daughter board has more than two conductive circuit layers, the first conductive hole can also electrically connect at least two inner conductive circuit layers in the daughter board.

[0042] Specifically, a through-hole can be opened on the daughter board, and a plating layer is formed in the through-hole through electroplating treatment. By removing a part of the plating layer in the first conductive hole on the second side of the daughter board facing away from its first side, a first back-drilled hole is formed; the first back-drilled hole can disconnect the conductive circuit layer it is connected to from the electrical connection with the first conductive hole at the position corresponding to the first back-drilled hole. Therefore, by performing back-drilling treatment to form the first back-drilled hole, the first conductive hole can electrically connect a specified one or more inner conductive circuit layers on the daughter board to the first conductive layer on the first side surface of the daughter board.

[0043] In this embodiment, the first conductive hole can be drilled at a position on the second side of the daughter board corresponding to the first conductive hole to remove a part of the plating layer in the first conductive hole, forming a first back-drilled hole; the drilling treatment can remove a part of the plating layer in the first conductive hole by reaming the through-hole, or a part of the plating layer in the through-hole can also be removed only through the drilling treatment.

[0044] Or in other embodiments, the method of drilling may not be adopted to remove a part of the plating layer in the first conductive hole. For example, methods such as etching or laser ablation can be used to remove a part of the plating layer in the first conductive hole to form a first back-drilled hole.

[0045] S103: Stack two sub-boards and fix them to form a mother board, where the first side of one sub-board is located on the side facing away from the other sub-board.

[0046] After forming the first conductive holes on the sub-boards, a connection layer can be provided between the two sub-boards to stack and fix the two sub-boards to form a mother board.

[0047] In this embodiment, the first conductive layers can be provided on the first sides of both sub-boards, and the first conductive holes as described above can be formed on the first conductive layers of both sub-boards. Alternatively, the first conductive layer can be provided only on one sub-board and the first conductive hole can be formed.

[0048] When the first conductive layers are provided on the first sides of both sub-boards and the first conductive holes are provided on the first conductive layers of both sub-boards, the second sides corresponding to the first sides facing away from each other of the two sub-boards can be arranged to face each other, so that the openings of the corresponding first back-drilled holes on the two sub-boards can be arranged to face each other. Among them, optionally, after the two sub-boards are stacked and fixed, the surfaces of the first sides of the two sub-boards can respectively form two opposite sides of the mother board; the surfaces of the second sides of the two sub-boards face each other and are both connected to the connection layer. At this time, the first conductive holes on the two sub-boards can be arranged coaxially. In one embodiment, the apertures of the first conductive holes on the two sub-boards can be set to be equal.

[0049] When the first conductive layer is provided only on one sub-board and the first conductive hole is formed, the first conductive layer on the sub-board with the first conductive hole can be provided on the side facing away from the other sub-board.

[0050] S104: Form a second through hole on the mother board and electroplate the second conductive hole to form a second conductive hole, and the second conductive hole is connected to the first conductive layer to electrically connect at least two specified conductive circuit layers on the mother board.

[0051] In this step, after forming the mother board described in the previous step S103, the mother board can be further processed to form a second conductive hole on the mother board.

[0052] Specifically, a second through hole can be formed on the mother board and the second conductive hole can be electroplated to form a second conductive hole, and the second conductive hole is connected to the first conductive layer to electrically connect at least two specified conductive circuit layers on the mother board. Among them, the formation method of the second conductive hole can be the same as that of the first conductive hole and will not be elaborated here.

[0053] Among them, the second conductive hole can electrically connect at least one conductive line layer on one sub-board to at least one conductive line layer on the other sub-board. The plating layer in the second conductive hole can be connected to the first conductive layer on the surface of the mother board, so that the first conductive layer is electrically connected to the second conductive hole.

[0054] After the preparation of the second conductive hole is completed, the first conductive layer on the surface of the mother board can be patterned, so that multiple conductive lines can also be formed on the first conductive layer on the surface of the mother board.

[0055] Among them, on the first conductive layer, the conductive lines connected to the first conductive hole and the conductive lines connected to the second conductive hole can have the same thickness.

[0056] Therefore, in this embodiment, by connecting both the first conductive hole and the second conductive hole to the first conductive layer, the electromagnetic shielding loss at the opening positions of the first conductive hole and the second conductive hole can be avoided, so that the signal transmission efficiency of the formed circuit board can be improved and the signal transmission loss can be reduced.

[0057] Further, please refer to Figures 3a - 3j . Among them, Figures 3a - 3j is a schematic flow chart of another embodiment of a method for manufacturing a circuit board provided by this application.

[0058] Among them, the method for manufacturing a circuit board can specifically include the following steps:

[0059] 1. Prepare at least two sub-boards.

[0060] Please refer to Figure 3a . In this step, the sub-board 100 can be formed by laminating a multi-layer substrate 110 and a multi-layer conductive line layer 120 on one side. Among them, a first conductive layer 111 is provided on the surface of the first side 101 of the two sub-boards 100.

[0061] In this step, the first conductive layer 111 can entirely cover the surface of the first side 101 of the sub-board 100. Specifically, the first conductive layer 111 can be formed by attaching a metal foil (such as a copper foil) to the surface of the first side 101 of the sub-board 100.

[0062] 2. Form a first conductive hole on the sub-board.

[0063] Please refer to Figures 3b - 3c . In this step, the sub-board 100 formed in the previous step can be perforated, so as to form a first conductive hole 130 on the sub-board 100.

[0064] Specifically, a first through-hole 131 can be formed on the daughter board 100 first. Among them, the first through-hole 131 can sequentially penetrate through multiple substrate layers 110 and multiple conductive circuit layers 120 of the daughter board 100. Then, through electroplating, an electroplated layer 132 can be formed on the inner wall of the first through-hole 131, so that a first conductive hole 130 can be formed. Among them, the electroplated layer 132 of the first conductive hole 130 can be connected to the first conductive layer 111 on the surface of the first side 101 so that the conductive through-hole is electrically connected to the first conductive layer 111; further, the electroplated layer 132 in the first conductive hole 130 can also be electrically connected to other conductive circuit layers 120 of the daughter board 100, so as to electrically connect at least one conductive circuit layer 120 connected by the first conductive hole 130 to the first conductive layer 111.

[0065] Among them, optionally, the first through-hole 131 can be formed by mechanically drilling the daughter board 100; or it can also be formed by laser drilling or other methods.

[0066] Please refer to Figure 3d , after forming the electroplated layer 132 on the inner wall of the first through-hole 131 to form the first conductive hole 130, the first conductive hole 130 can also be back-drilled to form a first back-drilled hole 133.

[0067] Specifically, the first through-hole 131 can be reamed at a position corresponding to the first through-hole 131 on the surface of the second side 102 of the daughter board 100, so as to remove the electroplated layer 132 on a partial hole section in the first through-hole 131 to form a first back-drilled hole 133. The other hole sections of the first through-hole 131 that are not reamed and the electroplated layer 132 on this hole section can electrically connect at least two specified conductive circuit layers 120.

[0068] Among them, the first back-drilled hole 133 can disconnect the electrical connection of the multiple conductive circuit layers 120 connected thereto at this position. Therefore, by opening the first back-drilled hole 133, one or more specified conductive circuit layers 120 on the daughter board 100 can be electrically connected through the first conductive hole 130, and the one or more conductive circuit layers 120 can further be electrically connected to the first conductive layer 111 through the first conductive hole 130.

[0069] By using the above method, multiple daughter boards 100 can be processed, and the first conductive holes 130 as described above can be formed on all the multiple daughter boards 100.

[0070] 3. Stack and fix two daughter boards to form a mother board.

[0071] Please refer to Figure 3e , in this step, two daughter boards 100 can be stacked to form a mother board 10.

[0072] Specifically, the second sides 102 of the two daughter boards 100 can be arranged to face each other, and by arranging a connection layer 140 between the two daughter boards 100, the two daughter boards 100 can be fixedly connected. Among them, in the mother board 10, the openings of the first back drill holes 133 on the second sides 102 of the two daughter boards 100 can be arranged corresponding to each other, so that the first conductive holes 130 of the two daughter boards 100 are coaxially arranged. At this time, the surfaces of the first sides 101 of the daughter boards 100 can be respectively located on the opposite sides of the mother board 10.

[0073] In this step, a prepreg can be arranged between the two daughter boards 100, and the connection layer 140 can be formed by thermocompression of the two daughter boards 100 and the prepreg.

[0074] Optionally, a window can be arranged at the position of the prepreg corresponding to the opening of the first back drill hole 133, so that the two daughter boards 100 can be communicated through the corresponding first back drill holes 133 and the window on the prepreg.

[0075] 4. Form a second conductive hole on the mother board.

[0076] Please refer to Figures 3f - 3h , after forming the mother board 10 as described above, a second conductive hole can be further opened on the mother board 10.

[0077] In this step, a protective layer 150 can be covered on the first conductive layers 111 on the opposite sides of the mother board 10 first.

[0078] The protective layer 150 can be formed by pasting a protective film on the surface of the mother board 10. For example, an insulating film such as a PET (polyethylene glycol terephthalate) film, a PI (Polyimide) film or a PP (polypropylene) film can be pasted on the surface of the first conductive layer 111 through glue; or a prepreg can be pasted on a metal sheet such as a copper foil, the prepreg is pasted on the surface of the first conductive layer 111, and then through thermocompression, the prepreg is in a molten state, and after the molten prepreg is cooled and fixed, the metal sheet can be pasted on the first conductive layer 111. At this time, the metal sheet and the first conductive layer 111 can be isolated by the prepreg; or an insulating glue can be arranged on the metal sheet to paste the metal sheet on the surface of the first conductive layer 111, thereby forming the protective layer 150.

[0079] Alternatively, in other embodiments, the protective layer 150 can also be formed by covering a protective material on the surface of the mother board. For example, an insulating material can be coated on the surface of the first conductive layer 111 to form the protective layer 150; alternatively, a prepreg can be placed on the surface of the first conductive layer 111, and through a hot pressing operation, the prepreg can be formed into the protective layer 150.

[0080] Please further refer to Figure 3g , after forming the protective layer 150, the mother board 10 can be subjected to a hole-opening process to form a second through hole 161 on the mother board 10; through an electroplating process, an electroplated layer 162 can be formed on the inner wall of the second through hole 161, wherein the electroplated layer 162 can electrically connect the first conductive layers 111 on the two opposite sides of the mother board 10 and one or more specified conductive circuit layers 120 inside the mother board 10.

[0081] Please further refer to Figures 3h - 3i , after forming the electroplated layer 162, the second through hole 161 can be reamed from one side of the mother board 10 to remove a part of the electroplated layer 162 inside the second through hole 161, thereby forming a second back drill hole 163. Similarly, the second back drill hole 163 can disconnect the electrical connection of the first conductive layer 111 and / or the conductive circuit layer 120 it connects at the position of the second back drill hole 163; the remaining unreamed hole section of the second through hole 161 and the corresponding electroplated layer 162 on this hole section can form a second conductive hole 160. Therefore, by forming the second conductive hole 160, the conductive layer 111 on one side surface of the mother board 10 can be electrically connected to one or more specified conductive circuit layers 120 inside it.

[0082] 5. Pattern the first conductive layer on the surface layer of the mother board.

[0083] Please further refer to Figure 3j , after completing the setting of the second conductive hole 160, the first conductive layer 111 on the surface layer of the mother board 10 can be further patterned. The first conductive layer 111 on the surface layer of the mother board 10 can also form a conductive circuit layer with multiple conductive lines, and further, a preset functional circuit can be formed on the mother board 10.

[0084] Specifically, the protective layer 150 on the surface layer of the mother board 10 can be removed first, so that the first conductive hole 130 and the second conductive hole 160 covered by it are exposed.

[0085] Then, the first conductive layer 111 on the surface layer of the mother board 10 is patterned to form a conductive circuit layer with multiple conductive lines.

[0086] Specifically, a light-blocking layer formed of a photoresist material can be first covered on the conductive surface of the first conductive layer 111. By performing a light irradiation process on a preset area of the light-blocking layer, the light-blocking layer corresponding to this area can undergo a property change; by removing the light-blocking layer in the area where the property change occurs, the area corresponding to the first conductive layer 111 covered by it is exposed; by using methods such as etching to remove the exposed area of the first conductive layer 111, multiple conductive lines can be formed on the first conductive layer 111.

[0087] In this embodiment, patterning processing can be performed on the first conductive layers 111 on both opposite sides of the motherboard 10. After the patterning processing of the first conductive layers 111 on both opposite sides of the motherboard 10 is completed, the remaining light-blocking layer can also be removed, so that the required circuit board can be obtained.

[0088] In this embodiment, second conductive holes 160 as described above can be opened on both opposite sides of the motherboard 10. The second conductive holes 160 can electrically connect at least one conductive line layer 120 in each of the two daughter boards 100; thereby realizing signal transmission between the two daughter boards 100. The first conductive holes 130 and the second conductive holes 160 located on the same side of the motherboard 10 can be used for plugging and matching and electrically connecting with different connection parts of components.

[0089] Furthermore, the present application also provides a circuit board. Please refer to Figure 4 , Figure 4 which is a schematic structural diagram of an embodiment of a circuit board provided by the present application.

[0090] The circuit board 20 can be manufactured by using the manufacturing method of the circuit board as shown in Figure 2 or Figures 3a - 3j . The circuit board 20 can include two stacked daughter boards 200. A connection layer 250 can be provided between the two daughter boards 200 and the two daughter boards 200 are fixedly connected.

[0091] Wherein, each daughter board 200 includes at least one substrate 210 and at least two conductive line layers 220 that are alternately stacked.

[0092] As shown in Figure 4 , the circuit board 20 can be formed by stacking and fixing two daughter boards 200. In other embodiments, the circuit board 20 can also be formed by stacking and fixing three or more daughter boards 200.

[0093] The following will take the circuit board 20 formed by stacking and fixing two daughter boards 200 as an example for description.

[0094] In this embodiment, a first conductive layer 211 is provided on the surface of the first side 201 of at least one daughter board 200. Among them, as shown in Figure 4The two first conductive layers 211 of the two sub-boards 200 are respectively arranged on the two opposite sides of the two sub-boards 200. A first conductive hole 230 is provided on each sub-board 200, and the first conductive holes 230 on the two sub-boards 200 electrically connect at least two designated conductive circuit layers 220 in the corresponding sub-boards 200; the first conductive holes 230 on the two sub-boards 200 are connected to the first conductive layers 211 on the corresponding sub-boards 200.

[0095] The circuit board 20 is also provided with a second conductive hole 240, which penetrates through the two stacked sub-boards 200, and is used to electrically connect at least one conductive circuit layer 220 in each of the two sub-boards 200. Therefore, the two sub-boards 200 can be electrically connected through the second conductive hole 240, so that the electrical signal in one sub-board 200 can be transmitted to the other sub-board 200 through the second conductive hole 240.

[0096] Therefore, by connecting both the first conductive hole and the second conductive hole to the first conductive layer, the lack of electromagnetic shielding at the opening positions of the first conductive hole and the second conductive hole can be avoided, thereby improving the signal transmission efficiency of the circuit board and reducing the signal transmission loss.

[0097] In this embodiment, optionally, the first conductive layer 211 on both opposite sides of the circuit board 20 can be patterned to form a plurality of conductive circuits 2111, wherein the thickness of the first conductive layer 211 can be uniformly set and the thickness of each part of the first conductive layer 211 can be the same, so that the conductive circuit 2111 connected to the first conductive hole 230 and the conductive circuit 2111 connected to the second conductive hole 240 can have the same thickness and be arranged on the same plane. The first conductive hole 230 and the second conductive hole 240 located on the same side of the circuit board 20 can be plug-matched with the pins of the component and electrically connected. The component can be a connector, etc.

[0098] In the above embodiment, the manufacturing method of the second conductive via 240 can be specifically referred to in the above text, and will not be described in detail here. Among them, a second back-drilled hole 243 can be opened on at least one side of the second conductive via 240, and the conductive circuit layer 220 connected to it can be electrically disconnected at the position of the second back-drilled hole 243 through the second back-drilled hole 243, so that the second conductive via 240 can electrically connect at least two designated conductive circuit layers 220 in the circuit board 20.

[0099] Please read further Figure 4, in this embodiment, on the second sides of the two daughter boards 200 facing away from their first sides 201, first back drills 233 can be formed. The first back drills 233 can also be formed by removing a part of the plating layer in the first conductive holes 230. The formation method of the first back drills 233 can refer to the foregoing content and will not be elaborated here. Among them, the first back drills 233 can disconnect the conductive line layers 220 connected thereto at positions corresponding to the first back drills 233, so that the first conductive holes 230 electrically connect at least two specified conductive line layers 220 in the corresponding daughter boards 200.

[0100] The openings of the first back drills 233 on one of the daughter boards 200 can be docked with the openings of the first back drills 233 on the other daughter board 200, and by providing a window opening at the position of the connection layer 250 corresponding to the first back drills 233, the first back drills 233 on the two daughter boards 200 can be connected through the window opening of the connection layer 250.

[0101] Optionally, the first conductive holes 230 on the two daughter boards 200 can be set with the same aperture, and the first conductive holes 230 on one of the daughter boards 200 can be coaxial with the first conductive holes 230 on the other daughter board 200. This solution can achieve the formation of two conductive holes at one hole position of the circuit board. Among them, the first conductive holes 230 and the second conductive holes 240 on the same side of the circuit board 20 can be electrically connected to different connection parts of the component. Among them, the different connection parts of the component can be respectively inserted and matched with the first conductive holes 230 and the second conductive holes 240; or the different connection parts of the component can be respectively attached and electrically connected to the conductive lines 2111 connected by the first conductive holes 230 and the second conductive holes 240. Among them, the connection part of the component can be welded to the conductive line 2111 or bonded with a conductive adhesive.

[0102] Furthermore, the present application also provides an electronic device. The electronic device can include the circuit board 20 and the connector described above. Among them, the two connection parts of the connector are respectively inserted and matched with and electrically connected to the first conductive holes 230 and the second conductive holes 240 on the same side of the circuit board 20.

[0103] In summary, it is easy for those skilled in the art to understand that the beneficial effects of the present application are: by connecting both the first conductive hole and the second conductive hole to the first conductive layer, it is possible to avoid the lack of electromagnetic shielding at the opening positions of the first conductive hole and the second conductive hole. Therefore, the signal transmission efficiency of the formed circuit board can be improved, and the signal transmission loss can be reduced. Further, the manufacturing process of the circuit board provided in the present application is simple, the production time can be shortened, the production efficiency can be improved, and thus the production cost can be saved.

[0104] The above are only embodiments of the present application, and do not thereby limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall similarly be included within the patent protection scope of the present application.

Claims

1. A manufacturing method of a circuit board, characterized in that, The method for manufacturing the circuit board comprises: Prepare at least two sub-boards, each of which is formed by alternately stacking at least one substrate and at least two conductive circuit layers, and forming a first conductive layer on a first side of at least one of the sub-boards; A first through hole is opened on the first side of the sub-board and a first conductive hole is formed by electroplating, wherein the first conductive hole is connected to the first conductive layer, and the first conductive hole electrically connects at least two layers of the conductive circuit layer connected to it; removing a portion of the electroplating layer in the first conductive hole from a second side of the daughter board away from the first side to form a first back-drilled hole; The two sub-boards are stacked and fixed to form a motherboard, the surfaces of the two sub-boards with the openings of the first back-drilled holes are arranged facing each other, and a connection layer is arranged between the two sub-boards; the opening of the first back-drilled hole on one of the sub-boards is connected to the opening of the first back-drilled hole on the other sub-board, and the two sub-boards are fixedly connected, wherein the first side of one sub-board is located on the side away from the other sub-board, the connection layer is formed by arranging a prepreg between the two sub-boards, and by hot pressing the two sub-boards and the prepreg, and the connection layer has a window corresponding to the opening of the first back-drilled hole; A protective layer is provided on two opposite surfaces of the motherboard, wherein the protective layer partially covers the opening of the first conductive hole; Forming a second through hole on the motherboard, and electroplating the second through hole to form a second conductive hole, wherein the second conductive hole is connected to the first conductive layer, and electrically connecting at least two designated conductive circuit layers on the motherboard; removing the protective layer to expose the first conductive via and the second conductive via; Patterning the conductive circuit layers on the opposite sides of the motherboard to form a plurality of conductive circuits with a preset pattern; A portion of the electroplating layer in the second through hole is removed from one side of the motherboard to form a second back-drilled hole.

2. The manufacturing method of the circuit board according to claim 1, characterized in that The first side of the two sub-boards is formed with the first conductive layer, and the first side of the two sub-boards is opened with the first conductive hole.

3. The manufacturing method of the circuit board according to claim 1, characterized in that The step of connecting the opening of the first back-drilled hole on one of the daughter boards with the opening of the first back-drilled hole on the other daughter board comprises: The first back-drilled hole on one of the daughter boards is arranged coaxially with the first back-drilled hole on the other daughter board.

4. The method for manufacturing a circuit board according to claim 1, characterized in that: The protective layer is formed by attaching a protective film to the surface of the mother board; or The protection layer is formed by covering the surface of the mother board with a protection material.

5. The method for manufacturing a circuit board according to claim 1, characterized in that: At least one of the conductive circuit layers in each of the two sub-boards is electrically connected through the second conductive hole; The first conductive hole and the second conductive hole located on the same side of the motherboard are used for plugging and matching with different connecting parts of the component and for electrical connection.

6. A circuit board, which is prepared by the manufacturing method of the circuit board according to any one of claims 1-5, characterized in that, The circuit board comprises: Two stacked sub-boards, each of which comprises at least one substrate and at least two conductive circuit layers, and the at least one substrate and the at least two conductive circuit layers are stacked and arranged alternately; A first conductive layer is disposed on a first side of at least one of the sub-boards, wherein the first side of the sub-board is located away from another sub-board; A first conductive via, wherein the first conductive via is connected to the first conductive layer, and the first conductive via is used to electrically connect at least two designated conductive circuit layers on the corresponding sub-board; and A second conductive hole, the second conductive hole is connected to the first conductive layer, and the second conductive hole is used to electrically connect at least two layers of the conductive circuit layers designated by the two sub-boards; A first back-drilled hole is formed on a second side of the daughter board away from the first side, wherein the first back-drilled hole is formed by removing a portion of the electroplating layer in the first conductive hole; A second back-drilled hole is formed on at least one side of the second conductive hole; The second side surfaces of the two sub-boards facing away from the first side are arranged facing each other, and the opening of the first back-drilled hole on one sub-board is connected to the opening of the first back-drilled hole on the other sub-board; A connection layer is provided between the two sub-boards to fixedly connect the two sub-boards; The connection layer has a window corresponding to an opening of the first back-drilled via.

7. The circuit board according to claim 6, characterized in that: The first side of the two sub-boards is formed with the first conductive layer, and the first side of the two sub-boards is opened with the first conductive hole.

8. The circuit board according to claim 7, characterized in that: The first back-drilled hole on one of the daughter boards is coaxially arranged with the first back-drilled hole on the other daughter board.

9. The circuit board according to claim 7, characterized in that: The connection layer is formed by hot pressing a prepreg.

10. The circuit board according to claim 6, characterized in that: At least one of the conductive circuit layers in each of the two sub-boards is electrically connected through the second conductive hole; The first conductive via and the second conductive via located on the same side of the motherboard are used to electrically connect to different connecting parts of the component.

11. The circuit board according to claim 6, characterized in that: The first conductive layer has a uniform thickness, and the thickness is equal at all locations.

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