A manufacturing method of a circuit board

Abstract

The present application discloses a circuit board and a manufacturing method thereof. The manufacturing method of the circuit board includes: preparing two sub-boards, and forming a first conductive layer 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, and the first conductive hole electrically connects the first conductive layer and at least one conductive circuit layer; laminating and fixing the two sub-boards to form a mother board, wherein the opposite sides of the mother board are respectively the first sides of the corresponding sub-boards; covering a protective layer on the opposite side surfaces of the mother board, and the protective layer partially covers the first conductive hole; opening a first slot on the protective layer to expose the first side of the corresponding sub-board from the first slot; forming a second through-hole penetrating the mother board at the position of the first slot, and the second through-hole communicates along the direction of penetrating the opposite sides of the mother board; electroplating the first through-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; removing the protective layer.

Description

Technical Field

[0001] This application belongs to the technical field of printed circuit board processing, and particularly relates to a method for manufacturing a circuit board. 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 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 method for manufacturing a circuit board to solve the above technical problems.

[0004] To solve the above technical problems, a technical solution adopted by this application is: to provide a method for manufacturing a circuit board, the method for manufacturing 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 sub-boards stacked, 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 daughter boards, and the first side of the daughter board is on a side facing away from the other daughter board;

[0012] A first conductive hole is formed by opening a first through hole on the first side of the daughter 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 daughter 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 daughter 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. BRIEF 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 based on 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 - 3k 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. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art 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 positional relationship and movement conditions between components in a certain specific posture (as shown in the accompanying drawings). If this 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 flow chart of an embodiment of an existing method for manufacturing a 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 arranged alternately.

[0025] Among them, one surface of the sub-board is a conductive circuit layer 320, and a first through hole can be opened on this surface of the sub-board. Then, electroplating is performed on the first through hole to form an electroplated layer in the first through hole, 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 shown Figure 1c in the figure, after forming the conductive line (or pad) 321 connected to the first conductive hole 330 on the daughter board, the two daughter boards can be stacked and fixed to form a mother board, and then the second conductive hole 360 can be formed on the mother board. Correspondingly, the forming method of the second conductive hole 360 can be the same as that of the first conductive hole 330. The difference is that the second conductive hole 360 can penetrate through the two daughter boards in sequence, and the second conductive hole 360 can electrically connect at least two specified conductive line layers 320 in the mother board. For example, the second conductive hole 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] Specifically, forming the second conductive hole 360 includes first forming a second through hole on the mother board, and then performing electroless copper plating, black hole or black shadow treatment on the inner wall of the second through hole, so as to form a conductive layer on the inner wall of the second through hole; this conductive layer can be used as a seed layer, and then an electroplated layer is formed based on this seed layer to obtain the second conductive hole 360.

[0029] When performing electroless copper plating, black hole or black shadow treatment on the second through hole, 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 hole 330 and causing the first conductive hole 330 to be corroded and damaged, it is necessary to seal the opening of the first conductive hole 330.

[0030] Generally speaking, a covering layer 350 can usually be provided on one side of the opening of the first conductive hole 330 to seal the opening of the first conductive hole 330. Among them, the covering layer 350 can be fixedly attached to the first conductive hole 330 through a connecting layer 352 to encapsulate the opening of the first conductive hole 330, and the covering layer 350 can be a metal layer formed by a thin sheet such as copper foil. At this time, due to the provision of the covering layer 350 in the process of forming the second conductive hole 360, the opening of the second conductive hole 360 is located on the side of the covering layer 350 away from the mother board, so that the position of the opening of the second conductive hole 360 is not flush with the position of the opening of the first conductive hole 330. Therefore, when the first conductive hole 330 and the second conductive hole 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 hole 330 and the second conductive hole 360, which will increase the signal transmission loss of the entire circuit board.

[0031] It should be noted that conductive vias can also be formed on each daughter board, and then the daughter boards are stacked to form a mother board so that the conductive vias on different daughter boards are connected, thereby splicing to form the second conductive hole 360. Although this solution can make the metal layers connected by the openings on one side of the mother board of the first conductive hole 330 and the second conductive hole 360 on the same layer, it is difficult to ensure an effective electrical connection between the conductive vias of each daughter board, and it is necessary to electroplate the spliced second conductive hole 360 again, 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 for a circuit board. Please refer to Figure 2 , Figure 2 which is a schematic flow chart of an embodiment of a manufacturing method for a circuit board provided by the present application. In one embodiment, the manufacturing method for the circuit board of the present application includes the following steps:

[0033] S101: Prepare at least two daughter boards, each daughter board is 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 is formed on the first side of at least one daughter board.

[0034] In this step, at least two daughter boards need to be prepared first. Each daughter board can be formed by sequentially and alternately laminating at least one layer of substrate and at least two layers of conductive circuit layers.

[0035] Among them, a first conductive layer is formed on the first side surface of at least one daughter board. The first conductive layer can be a metal layer provided on the first side surface of the daughter board, and the first conductive layer can cover at least a part or all of the area of the first side surface of the daughter board. The first conductive layer can be patterned to form multiple conductive lines with a preset pattern. For the subsequent processing of the first conductive layer, please refer to the following text in detail.

[0036] Among them, it should be noted that the inner conductive circuit layers of each daughter board can all be conductive circuit layers with multiple conductive lines that have been patterned.

[0037] 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.

[0038] Among them, each daughter board can be a single-layer circuit board composed of one layer of substrate and two layers of conductive circuit layers provided on opposite sides of this layer of substrate; or it can also be a multi-layer circuit board formed by sequentially and alternately laminating at least two layers of substrates and multiple layers of conductive circuit layers.

[0039] S102: A first through hole is formed on the first side of the daughter board and electroplated to form a first conductive hole, which is connected to the first conductive layer, and the first conductive hole electrically connects the first conductive layer and at least one conductive circuit layer.

[0040] Specifically, the first through hole can be formed on the first side (the side with the first conductive layer) of the daughter board. 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 the first conductive hole.

[0041] The first conductive hole is connected to the first conductive layer, and the first conductive hole is also connected to other conductive circuit layers in the corresponding daughter board. Specifically, the first conductive hole electrically connects at least two conductive circuit layers in the corresponding daughter board. For example, the first conductive hole can electrically connect the first conductive layer and the 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 layer conductive circuit layers in the daughter board.

[0042] Specifically, in some embodiments, a part of the plating layer in the first conductive hole is removed on the second side of the daughter board facing away from its first side to form a first back drill hole; the first back drill hole can disconnect the conductive circuit layer connected by the first conductive hole from the electrical connection with the first conductive hole at the position corresponding to the first back drill hole. Therefore, by performing a back drill process on the daughter board, the first conductive hole can disconnect the specified one or more inner layer conductive circuit layers on the daughter board from the electrical connection with 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 the position corresponding to the first conductive hole on the second side of the daughter board to remove a part of the plating layer in the first conductive hole to form a first back drill hole; the drilling process 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 by the drilling process.

[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, a part of the plating layer in the first conductive hole can be removed by etching or laser ablation to form a first back drill hole.

[0045] S103: At least two daughter boards are stacked and fixed to form a mother board, where the opposite sides of the mother board are respectively the first sides of the corresponding daughter boards.

[0046] Specifically, a first conductive layer can be provided on the first side of each of the two sub-boards, and first conductive holes as described above can be formed in the first conductive layers of the two sub-boards. The two sub-boards are stacked and fixed to form a mother board. The first sides of each sub-board are arranged facing away from each other, thus respectively forming the opposite sides of the mother board. That is to say, the second sides corresponding to the first sides facing away from each other of the two sub-boards can be arranged facing each other, so that the openings of the corresponding first back-drilled holes on the two sub-boards can face each other.

[0047] In some embodiments, a connection layer can be provided between the two sub-boards to stack and fix the two sub-boards to form a mother board. Specifically, the surfaces of the second sides of the two sub-boards (i.e., the surfaces where the first back-drilled holes are formed on the sub-boards) are arranged facing each other; the connection layer is provided between the two sub-boards, and both sub-boards are connected to the connection layer, and the openings of the first back-drilled holes of the two sub-boards are butted. 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.

[0048] S104: Cover protective layers on the opposite side surfaces of the mother board, and the protective layers partially cover the first conductive holes.

[0049] In this step, after completing the step of stacking and fixing at least two sub-boards to form a mother board, protective layers can be respectively covered on the opposite side surfaces of the mother board. That is to say, protective layers are provided on the first sides of the two sub-boards stacked and fixed to form the mother board. The protective layer can partially cover the first conductive holes.

[0050] Among them, the protective layer can have a size substantially the same as the surfaces of the opposite sides of the mother board. When the protective layer is covered on the mother board surface, it can partially cover the opening position of the first conductive hole located on this surface of the mother board to seal the opening of the first conductive hole.

[0051] S105: Open a first slot on the protective layer to expose the first side of the corresponding sub-board from the first slot.

[0052] After completing the covering of the protective layer, a first slot is opened on the protective layer to expose the first side of the corresponding sub-board from the first slot.

[0053] In some specific embodiments, part of the protective layer can be removed by etching, laser ablation or machining to form a first slot on the protective layer, so that the first conductive layer on the sub-board is exposed from the first slot.

[0054] S106: Form a second through-hole on the mother board, and the second through-hole and the first slot communicate along the direction penetrating the opposite sides of the mother board.

[0055] After the first slot is opened, a second through hole is formed on the mother board, and the second through hole and the first slot communicate with each other along the direction penetrating the two opposite sides of the mother board.

[0056] Specifically, a second through hole can be opened at the position of the first conductive layer exposed in the second slot, and the second through hole can penetrate the entire mother board.

[0057] S107: Electroplate the second through 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.

[0058] Specifically, in this step, the second through 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, which will not be elaborated here.

[0059] Among them, the second conductive hole can electrically connect at least one conductive circuit layer on one sub-board to at least one conductive circuit layer on another sub-board. The electroplated 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.

[0060] 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.

[0061] S108: Remove the protective layer.

[0062] In this step, after the second conductive hole is set, the remaining protective layer can be removed, so that the first conductive layer covered by the protective layer is exposed, and the electroplated metal on the inner walls of the first conductive hole and the second conductive hole is connected to the first conductive layer.

[0063] 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.

[0064] Furthermore, by first opening a first slot in the protective layer to expose a part of the first conductive layer from the first slot, and then opening a second through hole penetrating the mother board based on the first conductive layer exposed in the first slot, it is possible to avoid the problem that the processing accuracy of the second through hole cannot meet the preset requirements in the prior art when directly opening a second through hole penetrating the protective layer and the mother board at the corresponding position of the protective layer; and it is possible to avoid the residue of the opening of the protective layer from entering the second through hole on the mother board, so as not to affect the subsequent step of electroplating the second through hole to form a metal coating.

[0065] In this embodiment, after the preparation of the second conductive hole is completed and after step S108: removing the protective layer 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.

[0066] Alternatively, in other embodiments, after step S103 is completed and before step S104 is completed, the first conductive layer on the surface of the mother board can be patterned first, so that multiple conductive lines can also be formed on the first conductive layer on the surface of the mother board; then step S104 and subsequent steps are carried out.

[0067] Figures 3a - 3k It is a schematic flow chart of another embodiment of a method for manufacturing a circuit board provided by the present application. Further, in a specific embodiment, please refer to Figures 3a - 3k , the method for manufacturing a circuit board may specifically include the following steps:

[0068] 1. Prepare at least two daughter boards.

[0069] Please refer to Figure 3a , in this step, the daughter 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 daughter boards 100.

[0070] In this step, the first conductive layer 111 can entirely cover the surface of the first side 101 of the daughter 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 daughter board 100.

[0071] 2. Form a first conductive hole in the daughter board.

[0072] Please refer to Figures 3b - 3c , in this step, the daughter board 100 formed in the previous step can be drilled to form a first conductive hole 130 in the daughter board 100.

[0073] Specifically, a first through hole 131 can be formed in 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.

[0074] 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 means of laser drilling or the like.

[0075] 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 drill hole 133.

[0076] 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 part of the hole section in the first through hole 131 to form a first back drill 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.

[0077] Among them, the first back drill 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 drill hole 133, one or more than one 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 than one conductive circuit layers 120 can further be electrically connected to the first conductive layer 111 through the first conductive hole 130.

[0078] By adopting 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.

[0079] 3. Stack and fix two daughter boards to form a mother board.

[0080] Please refer to Figure 3e , in this step, two daughter boards 100 can be stacked to form a mother board 10.

[0081] Specifically, the second sides 102 of the two sub-boards 100 can be arranged facing each other, and a connection layer 140 is arranged between the two sub-boards 100, so that the two sub-boards 100 can be fixedly connected. Among them, in the mother board 10, the openings of the first back-drilled holes 133 on the second sides 102 of the two sub-boards 100 can be arranged corresponding to each other, so that the first conductive holes 130 of the two sub-boards 100 are coaxially arranged. At this time, the surfaces of the first sides 101 of the sub-boards 100 can be located on the opposite sides of the mother board 10 respectively.

[0082] In this step, a prepreg can be arranged between the two sub-boards 100, and the connection layer 140 is formed by thermocompression of the two sub-boards 100 and the prepreg.

[0083] Among them, optionally, a window can be arranged at the opening position of the prepreg corresponding to the first back-drilled hole 133, so that the two sub-boards 100 can be connected through the corresponding first back-drilled holes 133 of the two and the window on the prepreg.

[0084] 4. Form a second conductive hole on the mother board.

[0085] 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.

[0086] 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.

[0087] In some specific embodiments, the protective layer 150 can include an adhesive layer 151 and a protective base layer 152. Among them, the protective base layer 152 can be an insulating film or a metal film layer, and the adhesive layer 151 can be an adhesive or a cured sheet. Specifically, the protective base layer 152 can be an insulating film such as a PET (polyethylene glycol terephthalate) film, a PI (Polyimide) film or a PP (polypropylene) film. And these insulating films are pasted on the surface of the first conductive layer 111 through glue; or the protective base layer 152 is a metal thin sheet such as copper foil, a prepreg is pasted on these metal thin sheets, the prepreg is pasted on the surface of the first conductive layer 111, and then through thermocompression, the prepreg is in a molten state. After the molten prepreg is cooled and fixed, the metal thin sheet can be pasted on the first conductive layer 111. At this time, the metal thin sheet and the first conductive layer 111 can be isolated by the prepreg; or an insulating glue can also be arranged on the metal thin sheet to paste the metal thin sheet on the surface of the first conductive layer 111, so as to form the protective layer 150.

[0088] Alternatively, in other embodiments, the protective layer 150 can also be formed by covering the surface of the mother board with a protective material. 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.

[0089] Among them, in one embodiment, the adhesive layer 151 can be provided with a first clearance groove 153 at a position corresponding to the first conductive hole 130. Among them, by providing the first clearance groove 153, it can be prevented that when the protective layer 150 is formed, there is no adhesive layer 151 above the opening of the first conductive hole 130, so that the viscous substance forming the adhesive layer 151 can be prevented from entering the first conductive hole 130, thereby avoiding blockage of the first conductive hole 130.

[0090] Please further refer to Figure 3g , after the protective layer 150 is formed, a first slot 154 can be opened at a position corresponding to the second through hole 161 described later on the protective layer 150. The first slot 154 can expose the first conductive layer 111 at the position on the mother board where the second through hole 161 is to be opened.

[0091] In this step, when the protective layer 150 is formed by pasting an insulating film such as a PET film, a PI film or a PP film on the surface of the first conductive layer 111 with glue, a part of the protective layer 150 can be removed by laser ablation, thereby forming the first slot 154.

[0092] When the protective layer 150 is formed by pasting a metal sheet such as a copper foil on a prepreg and pasting the copper foil and the like on the surface of the first conductive layer 111 through heat curing of the prepreg, a part of the protective layer 150 can be etched away by etching, and the prepreg at the corresponding position can be removed, thereby forming the first slot 154.

[0093] When the protective layer 150 is formed by covering the surface of the mother board with a protective material, a part of the protective layer 150 can be milled away by mechanical means, thereby forming the first slot 154.

[0094] Among them, in an optional embodiment, the adhesive layer 151 can also be provided with a second clearance groove (not shown in the figure) at a position corresponding to the second through hole 16.

[0095] Please further refer to Figures 3g - 3h, after the first slot 154 is formed in the protective layer 150, a second via hole 161 penetrating the motherboard 10 can be further formed in the first conductive layer 111 exposed in the first slot 154. By electroplating the second via hole 161, an electroplated layer 162 can be formed on the inner wall of the second via hole 161. Among them, the first conductive layers 111 on the two opposite sides of the motherboard 10 and one or more specified conductive circuit layers 120 inside the motherboard 10 can be electrically connected through the electroplated layer 162.

[0096] Please refer further to Figures 3i - 3j , after the electroplated layer 162 is formed, the second via hole 161 can be reamed from one side of the motherboard 10 to remove a part of the electroplated layer 162 inside the second via hole 161, so as to form a second back drill hole 163. Similarly, the first conductive layer 111 and / or the conductive circuit layer 120 connected by the second back drill hole 163 can be disconnected from each other at the position of the second back drill hole 163; the remaining unreamed hole section of the second via hole 161 and the corresponding electroplated layer 162 on this hole section can form a second conductive via hole 160. Therefore, by forming the second conductive via hole 160, the conductive layer 111 on one side surface of the motherboard 10 can be electrically connected to one or more specified conductive circuit layers 120 on its inner layer.

[0097] 5. Pattern the first conductive layer on the surface of the motherboard.

[0098] Please refer further to Figure 3k , after the second conductive via hole 160 is set, the first conductive layer 111 on the surface of the motherboard 10 can be further patterned. The first conductive layer 111 on the surface of the motherboard 10 can also form a conductive circuit layer with multiple conductive lines, and then a preset functional circuit can be formed on the motherboard 10.

[0099] Specifically, the protective layer 150 on the surface of the motherboard 10 can be removed first, so that the first conductive via hole 130 and the second conductive via hole 160 covered by it are exposed.

[0100] Then, the first conductive layer 111 on the surface of the motherboard 10 is patterned to form a conductive circuit layer with multiple conductive lines.

[0101] 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 irradiating a preset area of the light blocking layer, the light blocking layer corresponding to this area can be changed in property; by removing the light blocking layer in the area where the property has changed, the area of the first conductive layer 111 covered by it is exposed; by using etching or other methods to remove the exposed area of the first conductive layer 111, multiple conductive lines can be formed on the first conductive layer 111.

[0102] In this embodiment, patterning processes can be performed on the first conductive layers 111 on the opposite sides of the motherboard 10. After the patterning processes are completed on the first conductive layers 111 on the opposite sides of the motherboard 10, the remaining light-blocking layers can be removed, so that the required circuit board can be obtained.

[0103] In this embodiment, second conductive holes 160 as described above can be formed on the opposite sides of the motherboard 10. The second conductive holes 160 can electrically connect at least one layer of conductive circuit layers 120 in each of the two daughter boards 100, thereby enabling signal transmission between the two daughter boards 100. The first conductive holes 130 and the second conductive holes 160 on the same side of the motherboard 10 can be used for plugging and matching and electrical connection with different connection parts of components.

[0104] 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.

[0105] The circuit board 20 can be manufactured by using the manufacturing method of the circuit board as shown in Figure 2 or Figures 3a - 3k . 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 can be fixedly connected.

[0106] Each daughter board 200 includes at least one substrate 210 and at least two conductive circuit layers 220 that are alternately stacked.

[0107] 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.

[0108] The following takes the circuit board 20 formed by stacking and fixing two daughter boards 200 as an example for illustration.

[0109] 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. As shown in Figure 4 , the two first conductive layers 211 of the two daughter boards 200 are respectively provided on the opposite sides of the two daughter boards 200. Each daughter board 200 is provided with a first conductive hole 230. The first conductive holes 230 on the two daughter boards 200 electrically connect at least two specified conductive circuit layers 220 in their corresponding daughter boards 200. The first conductive holes 230 on the two daughter boards 200 are both connected to the first conductive layer 211 on their corresponding daughter boards 200.

[0110] The circuit board 20 is also provided with a second conductive hole 240, which penetrates through two stacked sub-boards 200. The second conductive hole 240 is used to electrically connect at least one conductive line layer 220 in each of the two sub-boards 200. Therefore, an electrical connection can be formed between the two sub-boards 200 through the second conductive hole 240, so that an electrical signal in one sub-board 200 can be transmitted to the other sub-board 200 through the second conductive hole 240.

[0111] Therefore, by connecting both the first conductive hole and the second conductive hole to the first conductive layer, electromagnetic shielding loss can be avoided 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.

[0112] In this embodiment, optionally, the first conductive layers 211 on the opposite sides of the circuit board 20 can each be formed with a plurality of conductive lines 2111 through patterning. Among them, the thickness of the first conductive layer 211 can be uniformly set and the thicknesses at various positions of the first conductive layer 211 can be the same, so that the conductive lines 2111 connected to the first conductive hole 230 and the conductive lines 2111 connected to the second conductive hole 240 have equal thicknesses and are disposed on the same plane. Among them, the first conductive hole 230 and the second conductive hole 240 on the same side of the circuit board 20 can be inserted and matched with the pins of the component and electrically connected. The component can be a connector or the like.

[0113] In the above embodiment, the manufacturing method of the second conductive hole 240 can be specifically referred to the foregoing, and will not be elaborated here. Among them, a second back drill hole 243 can be opened on at least one side of the second conductive hole 240. Through the second back drill hole 243, the conductive line layer 220 connected thereto can be disconnected from the electrical connection at the position of the second back drill hole 243. Therefore, the second conductive hole 240 can electrically connect at least two specified conductive line layers 220 in the circuit board 20.

[0114] Please further refer to Figure 4 , in this embodiment, first back drill holes 233 can be opened on the second sides of the two sub-boards 200 facing away from their first sides 201. The first back drill holes 233 can also be formed by removing part of the plating layer in the first conductive hole 230. The formation method of the first back drill holes 233 can be referred to the foregoing and will not be elaborated here. Among them, the first back drill holes 233 can disconnect the conductive line layer 220 connected thereto from the electrical connection at the position corresponding to the first back drill holes 233, so that the first conductive hole 230 can electrically connect at least two specified conductive line layers 220 in the corresponding sub-board 200.

[0115] The opening of the first back-drilled hole 233 on one of the sub-boards 200 can be connected to the opening of the first back-drilled hole 233 on the other sub-board 200, and by setting a window at the position corresponding to the first back-drilled hole 233 on the connecting layer 250, the first back-drilled holes 233 on the two sub-boards 200 can be connected through the window of the connecting layer 250.

[0116] Optionally, the first conductive holes 230 on the two sub-boards 200 can be set with the same aperture, and the first conductive hole 230 on one sub-board 200 can be coaxially arranged with the first conductive hole 230 on the other sub-board 200. This solution can realize the opening of two conductive holes on one hole position of the circuit board. The first conductive hole 230 and the second conductive hole 240 located on the same side of the circuit board 20 can be electrically connected to different connecting parts of the component, wherein the different connecting parts of the component can be plugged and matched with the first conductive hole 230 and the second conductive hole 240 respectively; or the different connecting parts of the component can be respectively attached and electrically connected to the conductive circuit 2111 connected to the first conductive hole 230 and the second conductive hole 240, wherein the connecting part of the component can be welded to the conductive circuit 2111, or bonded with conductive glue.

[0117] Furthermore, the present application also provides an electronic device. The electronic device may include the circuit board 20 and the connector described above, wherein the two connecting parts of the connector are respectively plugged and matched with the first conductive hole 230 and the second conductive hole 240 located on the same side of the circuit board 20 and are electrically connected.

[0118] In summary, it is easy for a person skilled in the art to understand that the beneficial effect of the present application is that 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 position 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. Furthermore, the manufacturing method of the circuit board provided in the present application has a simple manufacturing process, which can shorten the production time, improve the production efficiency, and thus save the production cost.

[0119] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A manufacturing method of a circuit board, characterized in that The manufacturing method of the circuit board includes: Preparing two sub-boards, each of the sub-boards being formed by sequentially and alternately laminating at least one substrate and at least two conductive circuit layers, and a first conductive layer being formed on the first side of at least one of the sub-boards; 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 the first conductive layer and at least one of the conductive circuit layers; Removing a part of the electroplated layer in the first conductive hole from the second side of the sub-board facing away from the first side to form a first back-drilled hole; Stacking and fixing the two sub-boards to form a mother board, wherein the opposite sides of the mother board are respectively the first sides of the corresponding sub-boards, and the first back-drilled hole on one of the sub-boards is arranged coaxially with the first back-drilled hole on the other sub-board; Covering protective layers on the opposite side surfaces of the mother board, the protective layers partially covering the first conductive holes; Opening a first slot on the protective layer to expose the first side of the corresponding sub-board from the first slot; Forming a second through-hole penetrating the mother board at the position of the first slot, the second through-hole communicating along the direction of penetrating the opposite two sides of the mother board; Electroplating the second through-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; Removing a part of the electroplated layer in the second through-hole from one side of the mother board to form a second back-drilled hole; Removing the protective layer.

2. The manufacturing method of the circuit board according to claim 1, wherein The step of opening a first slot on the protective layer to expose the first side of the corresponding sub-board from the first slot includes: Removing the area of the protective layer corresponding to the second through-hole by means of laser ablation or etching to form the first slot.

3. The manufacturing method of the circuit board according to claim 1 or 2, characterized in that, The protective layer includes an adhesive layer and a protective base layer; The step of covering protective layers on the opposite side surfaces of the mother board, the protective layers partially covering the first conductive holes includes: Covering the adhesive layer on the first side, and the adhesive layer is provided with a second clearance groove at a position corresponding to the second conductive hole; Covering the protective base layer on the adhesive layer and covering the second clearance groove together.

4. The manufacturing method of the circuit board according to claim 3, wherein The adhesive layer is provided with a first clearance groove at a position corresponding to the first conductive hole, and the first clearance groove communicates with the first conductive hole.

5. The manufacturing method of the circuit board according to claim 4, characterized in that, The first conductive layers are formed on the first sides of both of the two sub-boards, and the first conductive holes are opened on the first sides of both of the two sub-boards; The step of stacking and fixing at least two sub-boards to form a mother board includes: Arranging the surfaces of the two sub-boards with the openings of the first back-drilled holes facing each other, and arranging a connection layer between the two sub-boards; After docking the opening of the first back-drilled hole on one of the sub-boards with the opening of the first back-drilled hole on the other sub-board, fixedly connecting the two sub-boards.

6. The manufacturing method of the circuit board according to claim 5, characterized in that the connection layer is formed by disposing a prepreg between the two sub-boards and performing hot pressing on the two sub-boards and the prepreg; the connection layer has a window corresponding to the opening of the first back drill hole.

7. The manufacturing method of the circuit board according to claim 6, characterized in that, After the step of forming a second through hole on the mother board and electroplating the second through hole to form a second conductive hole, it further includes: removing the protective layer to expose the first conductive hole and the second conductive hole; patterning the conductive circuit layers on the opposite surfaces of the mother board to form a plurality of conductive circuits having a preset pattern.

8. The manufacturing method of the circuit board according to claim 1, characterized in that each at least one conductive circuit layer in the two sub-boards is electrically connected through the second conductive hole; the first conductive hole and the second conductive hole on the same side of the mother board are used for plugging and matching and electrically connecting with different connection parts of the component.

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