A circuit board and a method for manufacturing the same

Abstract

The present invention discloses a circuit board and a manufacturing method thereof, the manufacturing method of the circuit board comprising: obtaining a pre-processed circuit board; wherein the pre-processed circuit board comprises a core board and a first metal base arranged on the core board, and a first circuit layer is formed on the surface of the core board; a thickening layer is covered on the pre-processed circuit board and pressed, the thickening layer comprises a third metal layer and a dielectric layer, and the dielectric layer is arranged between the first circuit layer and the third metal layer; a second metal base is formed on the first metal base; and the third metal layer is patterned to form a second circuit layer. The present application covers the thickening layer on the pre-processed circuit board, increases the copper thickness of the designated position of the pre-processed circuit board, forms the second metal base on the first metal base, forms the second circuit layer on the third metal layer, connects the first metal base with the second metal base, and realizes efficient heat dissipation of each layer in a high-density interconnected printed circuit board with directional positioning, while avoiding occupying wiring space.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board processing, and in particular to a circuit board and a manufacturing method thereof. Background Art

[0002] With the development of science and technology, people have higher and higher requirements for the integration of integrated circuit boards. In order to meet such requirements, multi-layer printed circuit boards have emerged. At present, electronic products are developing towards light, thin, small, high-density and multifunctionality. The assembly density and integration of electronic components on multi-layer printed circuit boards are getting higher and higher, and more and more attention is paid to the heat dissipation of circuit boards. At present, one of the heat dissipation solutions for high-density printed circuit boards is to embed a metal base (such as a copper base, an aluminum base, etc.) in the layer or position where heat dissipation is required in the printed circuit board to transfer heat and then achieve heat dissipation. However, the metal base in this method needs to be customized separately, and the metal base is embedded in the printed circuit board, and the alignment accuracy is relatively low; and the metal base has thickness and size restrictions, which affects the production quality of the circuit board. Another method is to arrange a large-area micro-through hole array at the layer or position where heat dissipation is required in the printed circuit board, and the micro-through hole is electroplated and filled with copper to transfer heat and then achieve heat dissipation. However, in this method, the through hole array position cannot be wired, which occupies wiring space. Summary of the invention

[0003] The main technical problem solved by the present invention is to provide a circuit board and a manufacturing method thereof, so as to solve the heat dissipation problem of high-density printed circuit boards in the prior art.

[0004] In order to solve the above technical problems, the first technical solution adopted by the present invention is: to provide a method for manufacturing a circuit board, the manufacturing method comprising: obtaining a pre-processed circuit board; wherein the pre-processed circuit board comprises a core board and a first metal base arranged on the core board, and a first circuit layer is formed on the surface of the core board; covering the pre-processed circuit board with a thickening layer and laminating it, the thickening layer comprises a third metal layer and a dielectric layer, and the dielectric layer is arranged between the first circuit layer and the third metal layer; forming a second metal base on the first metal base; patterning the third metal layer to form a second circuit layer.

[0005] Among them, the steps of obtaining a pre-processed circuit board specifically include: obtaining a core board, the core board including a substrate and a first metal layer and a second metal layer arranged on two opposite surfaces of the substrate; forming a connecting hole on the surface of the core board where the first metal layer is provided, so that the second metal layer is exposed through the connecting hole; covering the other surfaces of the first metal layer except for the connecting holes with a first photosensitive anti-plating layer; forming a first metal base in the connecting hole; removing the first photosensitive anti-plating layer, and patterning the surface of the first metal layer to form a first circuit layer.

[0006] Wherein, the surface of the first metal base is higher than the first circuit layer.

[0007] Among them, the steps of covering the thickening layer on the pre-treated circuit board and pressing it specifically include: obtaining a third metal layer; setting a dielectric layer on at least one surface of the third metal layer; forming a groove on the dielectric layer so that part of the surface of the third metal layer is exposed through the groove to obtain a thickening layer; facing the surface of the thickening layer with the groove toward the pre-treated circuit board so that the groove accommodates the exposed end of the first metal base; applying pressure to the thickening layer.

[0008] Wherein, in the step of applying pressure to the thickened layer, the third metal layer contacts the end surface of the first metal base.

[0009] Among them, the step of forming a second metal base on the first metal base specifically includes: removing the third metal layer in contact with the end surface of the first metal base to form a window, and the first metal base is exposed through the window; covering the other third metal layers except the window with a second photosensitive resist layer; forming a second metal base in the window; the step of patterning the third metal layer to form a second circuit layer includes: removing the second photosensitive resist layer; and etching the third metal layer to form a second circuit layer by a wet chemical method.

[0010] Among them, the step of patterning the third metal layer to form the second circuit layer specifically includes: forming the second circuit layer from the third metal layer by wet chemical etching, so that the end surface of the first metal base is exposed through the gap between the second circuit layers; the step of forming the second metal base on the first metal base specifically includes: covering the second photosensitive resist in the gap between the second circuit layer and other second circuit layers except the exposed first metal base, so that a window is formed on the second photosensitive resist, and the first metal base is exposed through the window; forming the second metal base in the window; removing the second photosensitive resist.

[0011] The width of the groove is greater than the width of the exposed end of the first metal base, and the difference between the width of the groove and the width of the first metal base is 10 microns to 200 microns.

[0012] Wherein, the first metal layer and the second metal layer are copper foils.

[0013] In order to solve the above technical problem, the second technical solution adopted by the present invention is: to provide a circuit board, which is manufactured by the above circuit board manufacturing method.

[0014] The beneficial effects of the present invention are as follows: different from the prior art, a circuit board and a manufacturing method thereof are provided, wherein the manufacturing method of the circuit board comprises: obtaining a pre-processed circuit board; wherein the pre-processed circuit board comprises a core board and a first metal base arranged on the core board, and a first circuit layer is formed on the surface of the core board; a thickening layer is covered on the pre-processed circuit board and pressed, the thickening layer comprises a third metal layer and a dielectric layer, and the dielectric layer is arranged between the first circuit layer and the third metal layer; a second metal base is formed on the first metal base; and the third metal layer is patterned to form a second circuit layer. The present application increases the copper thickness at a specified position of the pre-processed circuit board by covering the thickening layer on the pre-processed circuit board, forms a second metal base on the first metal base, forms a second circuit layer on the third metal layer, and connects the first metal base with the second metal base, thereby achieving efficient heat dissipation in a directional manner on each layer of a high-density interconnected printed circuit board, while avoiding occupying wiring space. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 It is a structural schematic diagram of the circuit board provided by the present invention;

[0017] Figure 2 It is a structural schematic diagram of an embodiment of a method for manufacturing a circuit board provided by the present invention;

[0018] Figure 3 It is a flow chart of a specific embodiment of a method for manufacturing a circuit board provided by the present invention;

[0019] Figure 4 yes Figure 3 A schematic structural diagram of step S201 in the provided method for manufacturing a circuit board;

[0020] Figure 5 yes Figure 3 A schematic structural diagram of step S202 in the provided method for manufacturing a circuit board;

[0021] Figure 6 yes Figure 3 A schematic structural diagram of step S203 in the provided method for manufacturing a circuit board;

[0022] Figure 7 yes Figure 3 A schematic structural diagram of step S204 in the provided method for manufacturing a circuit board;

[0023] Figure 8 yes Figure 3 A schematic diagram of the structure of the first stage of step S205 in the provided method for manufacturing a circuit board;

[0024] Fig. 9 yes Figure 3 A schematic diagram of the structure of step S206 in the provided method for manufacturing a circuit board;

[0025] Fig.10 yes Figure 3 A schematic structural diagram of step S207 in the provided method for manufacturing a circuit board;

[0026] Fig.11 yes Figure 3 A structural schematic diagram of step S208 in the provided method for manufacturing a circuit board;

[0027] Fig.12 yes Figure 3 A schematic structural diagram of step S209 in the provided method for manufacturing a circuit board;

[0028] Fig.13 yes Figure 3 A schematic structural diagram of step S210 in the provided method for manufacturing a circuit board;

[0029] Fig.14 yes Figure 3 A schematic structural diagram of step S212 in the provided method for manufacturing a circuit board;

[0030] Fig.15 yes Figure 3 A structural schematic diagram of step S213 in the provided method for manufacturing a circuit board;

[0031] Fig.16 It is a flow chart of another specific embodiment of the method for manufacturing a circuit board provided by the present invention;

[0032] Fig.17 yes Fig.16 A schematic diagram of the structure of step S308 in the provided method for manufacturing a circuit board;

[0033] Fig.18 yes Fig.16 A schematic diagram of the structure of step S309 in the provided method for manufacturing a circuit board;

[0034] Fig.19 yes Fig.16 A schematic structural diagram of step S310 in the provided method for manufacturing a circuit board;

[0035] Fig. 20 yes Fig.16 A structural schematic diagram of step S311 in the circuit board manufacturing method provided. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] In the following description, for the purpose of explanation rather than limitation, specific details such as specific system structures, interfaces, and technologies are provided to facilitate a thorough understanding of the present application.

[0038] The term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship. In addition, "many" in this article means two or more than two.

[0039] The terms "first", "second" and "third" in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second" and "third" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. All directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. The terms "including" and "having" in the embodiments of the present application and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or components inherent to these processes, methods, products or devices.

[0040] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive of other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0041] See also Figure 1 , Figure 1 1 is a schematic diagram of the structure of the circuit board provided by the present invention. This embodiment provides a circuit board 100. The circuit board 100 includes a substrate 111 and a first circuit layer 16 disposed on at least one surface of the substrate 111. A first metal base 15 is arranged in the substrate 111, and an end face of the first metal base 15 is higher than a surface of the first circuit layer 16 away from the substrate 111. A dielectric layer 22 is arranged in a gap between the surface of the first circuit layer 16 away from the substrate 111 and the first circuit layer 16. A second circuit layer 25 is arranged on a surface of the dielectric layer 22 away from the substrate 111 or the first circuit layer 16. The end face of the first metal base 15 is connected to the second metal base 24. When there is no need to arrange a new circuit layer on the second circuit layer 25 and there is no need to form a new metal base on the second metal base 24, the end face of the second metal base 24 away from the first metal base 15 can be flush with the end face of the second circuit layer 25; when there is a need to arrange a new circuit layer on the second circuit layer 25 and there is a need to form a new metal base on the second metal base 24, the end face of the second metal base 24 away from the first metal base 15 is higher than the second circuit layer 25.

[0042] The circuit board provided in this embodiment connects the first metal base with the second metal base so that the heat generated by the circuit board can be conducted to the outside through the first metal base and the second metal base, thereby solving the heat dissipation problem of the circuit board and achieving efficient heat dissipation of the directional positioning of the high-density interconnected printed circuit board while avoiding occupying wiring space.

[0043] See also Figure 2 , Figure 2 The figure is a schematic diagram of a method for manufacturing a circuit board according to an embodiment of the present invention. In this embodiment, a method for manufacturing a circuit board is provided. The circuit board in this embodiment can be a flexible circuit board or a hard-soft printed circuit board.

[0044] S11: Obtain a pre-processed circuit board; wherein the pre-processed circuit board includes a core board and a first metal base arranged on the core board, and a first circuit layer is formed on the surface of the core board.

[0045] Specifically, a core board is obtained, the core board includes a substrate and a first metal layer and a second metal layer arranged on two opposite surfaces of the substrate; a connection hole is formed on the surface of the core board provided with the first metal layer, so that the second metal layer is exposed through the connection hole; a first photosensitive resist is covered on the other surface of the first metal layer except for the connection hole; a first metal base is formed in the connection hole; the first photosensitive resist is removed, and the surface of the first metal layer is patterned to form a first circuit layer, so as to obtain a pre-treated circuit board. In a specific embodiment, the first circuit layer is formed on the first metal layer and / or the second metal layer by wet chemical etching. The first metal layer and the second metal layer are copper foils. In a specific embodiment, the surface of the first metal base is higher than the first circuit layer. In a preferred embodiment, the surface of the first metal base is flush with the surface of the first photosensitive resist away from the first metal layer.

[0046] S12: Covering the pre-processed circuit board with a thickening layer and laminating the thickening layer, wherein the thickening layer includes a third metal layer and a dielectric layer, and the dielectric layer is disposed between the first circuit layer and the third metal layer.

[0047] Specifically, a third metal layer is obtained; a dielectric layer is provided on at least one surface of the third metal layer; a groove is formed on the dielectric layer so that part of the surface of the third metal layer is exposed through the groove to obtain a thickened layer; the surface of the thickened layer provided with the groove is directed toward the pre-processed circuit board so that the groove accommodates the exposed end of the first metal base; and pressure is applied to the thickened layer. In the step of applying pressure to the thickened layer, the third metal layer contacts the end surface of the first metal base. In the step, the width of the groove is greater than the width of the exposed end of the first metal base, and the difference between the width of the groove and the width of the first metal base is 10 microns to 200 microns.

[0048] S13: forming a second metal base on the first metal base.

[0049] Specifically, the third metal layer in contact with the end surface of the first metal base is removed to form a window, and the first metal base is exposed through the window; the second photosensitive resist is covered on the third metal layer other than the window; and the second metal base is formed in the window. In an optional embodiment, a seed layer is deposited on the inner wall of the window; and the second metal base is formed in the window by electroplating. In a specific embodiment, the third metal layer in contact with the end surface of the first metal base is removed by one of laser ablation, ion cutting, ion polishing, and water jet cutting.

[0050] S14: forming a second circuit layer on the thickened layer.

[0051] Specifically, the second photosensitive resist is removed; the third metal layer is patterned by wet chemical etching to form a second circuit layer. In another optional embodiment, the third metal layer is patterned by wet chemical etching to form a second circuit layer, so that the end surface of the first metal base is exposed through the gap between the second circuit layers; the second photosensitive resist is covered in the gap between the second circuit layer and the other second circuit layers except the exposed first metal base, so that a window is formed on the second photosensitive resist, and the first metal base is exposed through the window. Then the second metal base is formed in the window; the second photosensitive resist is removed.

[0052] A circuit board and a manufacturing method thereof provided in this embodiment, the manufacturing method of the circuit board comprises: obtaining a pre-processed circuit board; wherein the pre-processed circuit board comprises a core board and a first metal base arranged on the core board, and a first circuit layer is formed on the surface of the core board; a thickening layer is covered on the pre-processed circuit board and pressed, the thickening layer comprises a third metal layer and a dielectric layer, and the dielectric layer is arranged between the first circuit layer and the third metal layer; a second metal base is formed on the first metal base; and the third metal layer is patterned to form a second circuit layer. The present application increases the copper thickness of a specified position of the pre-processed circuit board by covering a thickening layer on the pre-processed circuit board, forms a second metal base on the first metal base, forms a second circuit layer on the third metal layer, and connects the first metal base with the second metal base, thereby achieving efficient heat dissipation in a directional manner on each layer of a high-density interconnected printed circuit board, while avoiding occupying wiring space.

[0053] See also Figures 3 to 15 , Figure 3 It is a flow chart of a specific embodiment of a method for manufacturing a circuit board provided by the present invention; Figure 4 yes Figure 3 A schematic structural diagram of step S201 in the provided method for manufacturing a circuit board; Figure 5 yes Figure 3 A schematic structural diagram of step S202 in the provided method for manufacturing a circuit board; Figure 6 yes Figure 3 A schematic structural diagram of step S203 in the provided method for manufacturing a circuit board; Figure 7 yes Figure 3 A schematic structural diagram of step S204 in the provided method for manufacturing a circuit board; Figure 8 yes Figure 3 A schematic diagram of the structure of the first stage of step S205 in the provided method for manufacturing a circuit board; Fig. 9 yes Figure 3 A schematic diagram of the structure of step S206 in the provided method for manufacturing a circuit board; Fig.10 yes Figure 3 A schematic structural diagram of step S207 in the provided method for manufacturing a circuit board; Fig.11 yes Figure 3A structural schematic diagram of step S208 in the provided method for manufacturing a circuit board; Fig.12 yes Figure 3 A schematic structural diagram of step S209 in the provided method for manufacturing a circuit board; Fig.13 yes Figure 3 A schematic structural diagram of step S210 in the provided method for manufacturing a circuit board; Fig.14 yes Figure 3 A schematic structural diagram of step S212 in the provided method for manufacturing a circuit board; Fig.15 yes Figure 3 A schematic diagram of the structure of step S213 in the method for manufacturing a circuit board is provided. In this embodiment, a method for manufacturing a circuit board is provided. The circuit board in this embodiment can be a flexible circuit board or a hard-soft printed circuit board.

[0054] S201: Obtain a core board, the core board comprising a substrate and a first metal layer and a second metal layer disposed on two opposite surfaces of the substrate.

[0055] Specifically, see Figure 4 , obtain a core board 11, which includes a substrate 111 and a first metal layer 112 and a second metal layer 113 arranged on two opposite surfaces of the substrate 111. Among them, the material of the substrate 111 can be polyimide or other suitable materials. The materials of the first metal layer 112 and the second metal layer 113 are the same, and the materials of the first metal layer 112 and the second metal layer 113 can both be copper. The shape and size of the substrate 111, the first metal layer 112 and the second metal layer 113 are not limited and can be selected as needed. In one embodiment, the material of the substrate 111 is polyimide, and the first metal layer 112 and the second metal layer 113 are both copper layers. The first metal layer 112 and the second metal layer 113 completely cover the two opposite surfaces of the substrate 111.

[0056] S202: forming connection holes on the surface of the core board provided with the first metal layer, so that the second metal layer is exposed through the connection holes.

[0057] Specifically, see Figure 5 , clean the surface of the core board 11, and remove the debris on the surface of the core board 11. A first photosensitive resist layer is provided on the first metal layer 112 of the core board 11. In an optional embodiment, the first photosensitive resist layer may be applied only on the surface of the first metal layer 112 away from the substrate 111. In another optional embodiment, the first photosensitive resist layer may be applied only on the surface of the second metal layer 113 away from the substrate 111. In another optional embodiment, the first photosensitive resist layer may be applied on both the surfaces of the first metal layer 112 and the second metal layer 113 away from the substrate 111. In one embodiment, the first photosensitive resist layer may be a photoresist, covering the entire surface of the first metal layer 112 and / or the second metal layer 113.

[0058] In a specific embodiment, a first photosensitive resist layer is coated on the surface of the first metal layer 112 of the core board 11 away from the substrate 111. A mask plate designed as required is placed on the first photosensitive resist layer, and the first photosensitive resist layer with the mask plate on the surface is irradiated with ultraviolet light, so that the first photosensitive resist layer below the light-transmitting area of ​​the mask plate is cross-linked and cured under the action of light. The first photosensitive resist layer below the light-shielding area of ​​the mask plate is not irradiated with light, and the first photosensitive resist layer is not cross-linked and cured. The mask plate is removed, and the circuit board after illumination is cleaned with a developer, so that the cross-linked and cured portion of the first photosensitive resist layer on the first metal layer 112 on the core board 11 is retained, and the non-cross-linked and cured portion of the first photosensitive resist layer on the surface of the core board 11 is removed to form a notch in the first photosensitive resist layer, so that part of the surface of the first metal layer 112 is exposed through the notch.

[0059] In a specific embodiment, a wet chemical etching solution is used to etch the portion of the first metal layer 112 exposed through the gap, and the portion of the first metal layer 112 exposed through the gap is removed to form a first opening 131, so that a portion of the substrate 111 of the core board 11 is exposed through the first opening 131.

[0060] In another specific embodiment, dry etching can also be used to etch the portion of the first metal layer 112 exposed through the first opening 131. For example, the portion of the first metal layer 112 exposed through the first opening 131 can be removed by one of laser ablation, ion cutting, ion polishing, and water jet cutting to expose the substrate 111 and remove the first photosensitive resist layer.

[0061] The portion of the substrate 111 exposed by the first opening 131 is removed by laser ablation, thereby forming a through hole 114 on the substrate 111, so that the second metal layer 113 away from the position corresponding to the first opening 131 is exposed through the through hole 114. In an optional embodiment, when the substrate 111 is ablated from the first metal layer 112 to the second metal layer 113 to form the through hole 114, a portion of the second metal layer 113 is exposed through the through hole 114. In another optional embodiment, when the substrate 111 is ablated from the second metal layer 113 to the first metal layer 112 to form the through hole 114, a portion of the first metal layer 112 is exposed through the through hole 114.

[0062] The first opening 131 and the through hole 114 form a connecting hole 12 , and the second metal layer 113 or the first metal layer 112 away from the end of the first opening 131 is exposed through the connecting hole 12 .

[0063] S203: Covering the first metal layer with a first photoresist layer on the surface except the surface where the connection holes are provided.

[0064] Specifically, see Figure 6 , the first photosensitive resist 14 is covered on the surfaces of the first metal layer 112 and the second metal layer 113 away from the substrate 111 and other than the connection hole 12. The first photosensitive resist 14 may be a mask. In an optional embodiment, the first photosensitive resist 14 is provided on the surfaces of the first metal layer 112 and the second metal layer 113 away from the substrate 111, and the first photosensitive resist 14 covered on the first metal layer 112 and the second metal layer 113 is provided with a window 142 at a position corresponding to the connection hole 12. The window 142 of the first photosensitive resist 14 on the first metal layer 112 and the window 142 of the first photosensitive resist 14 on the second metal layer 113 are all provided corresponding to the connection hole 12, or the window 142 of the first photosensitive resist 14 on the first metal layer 112 and the window 142 of the first photosensitive resist 14 on the second metal layer 113 are partially provided corresponding to the connection hole 12.

[0065] S204: forming a first metal base in the connection hole.

[0066] Specifically, see Figure 7 , a first seed layer is deposited in the connecting hole 114, and the first seed layer can be a copper layer. The copper layer is distributed on the inner wall of the connecting hole 114. By depositing the copper layer, it is convenient to form the first metal base 15 in the connecting hole 114 in the subsequent steps, improve the bonding strength between the first metal base 15 and the circuit board, and then enhance the stability of the circuit board. The circuit board with the seed layer deposited on the inner wall of the connecting hole 114 is electroplated to form the first metal base 15 in the connecting hole 114 of the circuit board. When the end face of the first metal base 15 is flush with the surface of the first circuit layer 16, the dielectric layer 22 is easy to flow between the end face of the first metal base 15 and the third metal layer 21 during lamination. Therefore, the exposed end face of the first metal base 15 is higher than the surface of the first metal layer 112. In a preferred embodiment, the exposed end face of the formed first metal base 15 needs to be flush with the surface of the first photosensitive anti-plating layer 14 away from the first metal layer 112. Among them, the material of the first metal base 15 is preferably copper.

[0067] S205: removing the first photosensitive resist layer, and patterning the surface of the first metal layer to form a first circuit layer.

[0068] Specifically, see Figure 8, the first photosensitive resist 14 covering the first metal layer 112 and the second metal layer 113 is removed, and the end surface of the first metal base 15 is higher than the first metal layer 112 or the second metal layer 113 and away from the surface of the substrate 111. The first circuit layer 16 is formed on the first metal layer 112 and the second metal layer 113 respectively. In a specific embodiment, the first metal layer 112, the second metal layer 113 and the end surface of the first metal base 15 are covered with a first photosensitive resist layer, and after covering the first photosensitive resist layer with a suitable mask plate according to customer requirements, a second opening is formed on the first photosensitive resist layer by exposure and development, so that part of the first metal layer 112 and part of the second metal layer 113 are exposed through the second opening, and the part of the first metal layer 112 and part of the second metal layer 113 exposed through the second opening are removed, so that the substrate 111 is exposed through the second opening, and the first photosensitive resist layer covers part of the second metal layer 113 and the first metal layer 112 to form the first circuit layer 16. In a specific embodiment, a wet chemical etching solution is used to etch the portion of the first metal layer 112 and the second metal layer 113 exposed through the second opening. In another specific embodiment, the portion of the first metal layer 112 and the second metal layer 113 exposed through the second opening can also be removed by one of laser ablation, ion cutting, ion polishing, and water jet cutting to expose the substrate 111 and remove the first photosensitive resist layer.

[0069] S206: providing a thickening layer; wherein the thickening layer includes a third metal layer and a dielectric layer.

[0070] Specifically, first obtain the third metal layer 21 and the dielectric layer 22, fix the dielectric layer 22 on at least one surface of the third metal layer 21; form a groove 221 on the dielectric layer 22, expose part of the surface of the third metal layer 21 through the groove 221, and obtain the thickened layer 2.

[0071] In one specific embodiment, see Fig. 9 , prepare a third metal layer 21, which can be a copper foil. The material of the dielectric layer 22 can be a thermosetting material such as epoxy resin material, polyimide material, BT (Bismaleimide Triazine, a polymer of bismaleimide and triazine) resin, and the dielectric layer 22 can also be a semi-cured sheet. Fix the dielectric layer 22 to at least one surface of the third metal layer 21. In a specific embodiment, the dielectric layer 22 is adhered to a surface of the third metal layer 21. A groove 221 is formed on the dielectric layer 22 by laser ablation, so that part of the surface of the third metal layer 21 is exposed through the groove 221 to obtain the required thickening layer 2. Among them, the width of the groove 221 is greater than the exposed end face of the first metal base 15.

[0072] In another specific embodiment, the thickened layer 2 is a third metal layer 21 and a dielectric layer 22 that are independent of each other.

[0073] S207: The surface of the thickened layer provided with the groove is directed toward the pre-treated circuit board so that the groove accommodates the exposed end of the first metal base, and the pressing is performed.

[0074] Specifically, see Fig.10 , the side of the third metal layer 21 with the dielectric layer 22 is facing the pre-processed circuit board 1, so that the groove 221 corresponds to the end surface position of the first metal base 15 on the pre-processed circuit board 1, so that one end of the first metal base 15 is accommodated in the groove 221, and the dielectric layer 22 corresponds to the first circuit layer 16, and is heat-pressed, so that the dielectric layer 22 enters the first circuit layer 16 after being heated and semi-cured, and the formed circuits are isolated from each other. At the same time, the dielectric layer 22 flows to the groove 221 and is tightly attached to the side wall of the first metal base 15. The dielectric layer 22 also isolates the first circuit layer 16 from the third metal layer 21.

[0075] In another optional embodiment, the dielectric layer 22 is covered on the surface of the first circuit layer 16, the first metal base 15 is exposed, and the third metal layer 21 is covered on the dielectric layer 22, so that the third metal layer 21 is in contact with the end surface of the first metal base 15, and they are thermally pressed, so that the dielectric layer 22 is semi-cured by heat and enters the first circuit layer 16, and the formed circuits are isolated from each other. At the same time, the dielectric layer 22 flows to the groove 221 and is closely attached to the side wall of the first metal base 15. The dielectric layer 22 also isolates the first circuit layer 16 from the third metal layer 21.

[0076] S208: removing the third metal layer in contact with the end surface of the first metal base to form a window, and the first metal base is exposed through the window.

[0077] Specifically, see Fig.11 , the portion of the third metal layer 21 in contact with the end surface of the first metal base 15 is removed by exposure and development treatment and wet chemical etching solution to form a window 211 on the third metal layer 21, so that the end surface of the first metal base 15 is exposed through the window 211. In another embodiment, dry etching can also be directly used to remove the portion of the surface of the third metal layer 21 in contact with the end surface of the first metal base 15 to form the window 211, for example, by laser ablation, ion cutting, ion polishing, water jet cutting, etc. to remove the portion of the surface of the third metal layer 21 in contact with the end surface of the first metal base 15 to form the window 211, so that the end surface of the first metal base 15 is exposed through the window 211.

[0078] S209: Covering the other third metal layers except the window with a second photosensitive resist layer.

[0079] Specifically, see Fig.12, a second photosensitive resist layer 23 is coated on the other third metal layers 21 except the window 211 , and the second photosensitive resist layer 23 may be a photoresist.

[0080] S210: depositing a second seed layer on the inner wall of the window and the end surface of the first metal base exposed through the window.

[0081] Specifically, see Fig.13 , a second seed layer is deposited on the inner wall of the window 211 and the end surface of the first metal base 15 exposed through the window 211, and the second seed layer may be a copper layer. The copper layer is distributed on the inner wall of the window 211. By depositing the copper layer, it is convenient to form the second metal base 24 in the window 211 in the subsequent steps, improve the bonding strength between the second metal base 24 and the dielectric layer 22, and thus enhance the stability of the entire circuit board.

[0082] S211: forming a second metal base in the window by electroplating.

[0083] Specifically, the circuit board with the second seed layer deposited on the inner wall of the window 211 is electroplated to form the second metal base 24 in the window 211. The exposed end surface of the formed second metal base 24 needs to be flush with the surface of the second photosensitive resist 23 away from the third metal layer 21. The material of the second metal base 24 is preferably copper.

[0084] S212: removing the second photosensitive resist layer.

[0085] Specifically, see Fig.14 , the second photosensitive resist layer 23 on the third metal layer 21 is removed.

[0086] S213: The third metal layer is formed into a second circuit layer by wet chemical etching.

[0087] Specifically, see Fig.15 , a second photoresist layer is covered on the end surfaces of the third metal layer 21 and the second metal base 24, and after covering the second photoresist layer with a suitable mask plate according to customer requirements, a third opening is formed on the second photoresist layer by wet chemical etching, so that part of the third metal layer 21 is exposed through the third opening, and the part of the third metal layer 21 exposed through the third opening is removed, so that part of the dielectric layer 22 is exposed through the third opening, and the part of the third metal layer 21 covered by the second photoresist layer forms the second circuit layer 25. Among them, a wet chemical etching solution is used to etch the part of the third metal layer 21 exposed through the third opening. The part of the third metal layer 21 exposed through the third opening can also be removed by one of laser ablation, ion cutting, ion polishing, and water jet cutting, so that part of the dielectric layer 22 is exposed and the second photoresist layer is removed.

[0088] If it is necessary to form a new circuit layer on the second circuit layer 25, the surface of the second metal base 24 away from the first metal base 15 is made higher than the surface of the second circuit layer 25 away from the dielectric layer 22, and the process can directly jump to step S209 to form a new circuit layer on the second circuit layer 25, and form a new metal base on the surface of the second metal base 24 until the circuit board required by the customer is achieved.

[0089] If the number of circuit board layers required by the customer is reached, the surface of the second metal base 24 away from the first metal base 15 is flush with the surface of the second circuit layer 25 away from the dielectric layer 22. The heat released by each circuit layer is conducted to the surface of the circuit board through the interconnected metal bases. The pattern of each circuit layer can be different or the same; the size of the metal base can be the same or different, as long as the purpose of setting the metal base interconnection in each layer and not occupying the wiring space is achieved.

[0090] The manufacturing method of the circuit board provided in this embodiment includes: obtaining a pre-processed circuit board; wherein the pre-processed circuit board includes a core board and a first metal base arranged on the core board, and a first circuit layer is formed on the surface of the core board; a thickening layer is covered on the pre-processed circuit board and pressed, the thickening layer includes a third metal layer and a dielectric layer, and the dielectric layer is arranged between the first circuit layer and the third metal layer; a second metal base is formed on the first metal base; and the third metal layer is patterned to form a second circuit layer. The present application increases the copper thickness of the specified position of the pre-processed circuit board by covering the thickening layer on the pre-processed circuit board, forms a second metal base on the first metal base, forms a second circuit layer on the third metal layer, and connects the first metal base with the second metal base, thereby achieving efficient heat dissipation in a directional manner on each layer of a high-density interconnected printed circuit board, while avoiding occupying wiring space.

[0091] See also Figures 16 to 20 , Fig.16 It is a flow chart of another specific embodiment of the method for manufacturing a circuit board provided by the present invention; Fig.17 yes Fig.16 A schematic diagram of the structure of step S308 in the provided method for manufacturing a circuit board; Fig.18 yes Fig.16 A schematic diagram of the structure of step S309 in the provided method for manufacturing a circuit board; Fig.19 yes Fig.16 A schematic structural diagram of step S310 in the provided method for manufacturing a circuit board; Fig. 20 yes Fig.16 A schematic diagram of the structure of step S311 in the method for manufacturing a circuit board is provided. In this embodiment, a method for manufacturing a circuit board is provided. The circuit board in this embodiment can be a flexible circuit board or a hard-soft printed circuit board.

[0092] S301: Obtain a core board, the core board comprising a substrate and a first metal layer and a second metal layer disposed on two opposite surfaces of the substrate.

[0093] S302: forming connection holes on the surface of the core board provided with the first metal layer, so that the second metal layer is exposed through the connection holes.

[0094] S303: Covering the first metal layer with a first photoresist layer on the surface except the surface where the connection holes are provided.

[0095] S304: forming a first metal base in the connection hole.

[0096] S305: removing the first photosensitive resist layer, and patterning the surface of the first metal layer to form a first circuit layer.

[0097] S306: providing a thickening layer; wherein the thickening layer includes a third metal layer and a dielectric layer.

[0098] S307: The surface of the thickened layer provided with the groove is directed toward the pre-treated circuit board so that the groove accommodates the exposed end of the first metal base, and then pressed.

[0099] S308: The third metal layer is etched to form a second circuit layer by wet chemical etching, so that the end surface of the first metal base is exposed through the gap between the second circuit layers.

[0100] Specifically, see Fig.17 , a second photoresist layer is covered on the third metal layer 21, and after a suitable mask is covered on the second photoresist layer according to customer requirements, a third opening is formed on the second photoresist layer by exposure and development, so that part of the third metal layer 21 is exposed through the third opening, and the part of the third metal layer 21 exposed through the third opening is removed, so that part of the dielectric layer 22 and the first metal base 15 are exposed through the third opening, and the part of the third metal layer 21 covered by the second photoresist layer forms the second circuit layer 25. Among them, a wet chemical etching solution is used to etch the part of the third metal layer 21 exposed through the third opening. The part of the third metal layer 21 exposed through the third opening can also be removed by one of laser ablation, ion cutting, ion polishing, and water jet cutting, so that the first metal base 15 and part of the dielectric layer 22 are exposed, and the second photoresist layer is removed.

[0101] S309: Covering the gap between the second circuit layer and the other second circuit layers except the exposed first metal base with a second photosensitive resist layer, so that a window is formed on the second photosensitive resist layer, and the first metal base is exposed through the window.

[0102] Specifically, see Fig.18The second photosensitive resist 23 is covered in the gap between the second circuit layer 25 and the other second circuit layers 25 except the exposed first metal base 15, so that a window 211 is formed on the second photosensitive resist 23, and the first metal base 15 is exposed through the window 211. The second photosensitive resist 23 can be a photoresist.

[0103] S310: forming a second metal base in the window.

[0104] Specifically, see Fig.19 , a second seed layer is deposited on the inner wall of the window 211 and the end face of the first metal base 15 exposed through the window 211, and the second seed layer may be a copper layer. The copper layer is distributed on the inner wall of the window 211. By depositing the copper layer, it is convenient to form the second metal base 24 in the window 211 in the subsequent steps, improve the bonding strength between the second metal base 24 and the dielectric layer 22, and further enhance the stability of the entire circuit board. The circuit board with the second seed layer deposited on the inner wall of the window 211 is electroplated to form the second metal base 24 in the window 211. Among them, the exposed end face of the formed second metal base 24 needs to be flush with the surface of the second photosensitive anti-plating layer 23 away from the third metal layer 21. Among them, the material of the second metal base 24 is preferably copper.

[0105] S311: removing the second photosensitive resist coating.

[0106] Specifically, see Fig. 20 , the second circuit layer 25 and the second photosensitive resist layer 23 covering and filling the gaps in the second circuit layer 25 are removed.

[0107] The manufacturing method of the circuit board provided in this embodiment includes: obtaining a pre-processed circuit board; wherein the pre-processed circuit board includes a core board and a first metal base arranged on the core board, and a first circuit layer is formed on the surface of the core board; a thickening layer is covered on the pre-processed circuit board and pressed, the thickening layer includes a third metal layer and a dielectric layer, and the dielectric layer is arranged between the first circuit layer and the third metal layer; a second metal base is formed on the first metal base; and the third metal layer is patterned to form a second circuit layer. The present application increases the copper thickness of the specified position of the pre-processed circuit board by covering the thickening layer on the pre-processed circuit board, forms a second metal base on the first metal base, forms a second circuit layer on the third metal layer, and connects the first metal base with the second metal base, thereby achieving efficient heat dissipation in a directional manner on each layer of a high-density interconnected printed circuit board, while avoiding occupying wiring space.

[0108] The above description is only an implementation mode of the present invention, and does not limit the patent protection scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing a circuit board, characterized in that: The manufacturing method comprises: Obtain a pre-processed circuit board; wherein the pre-processed circuit board comprises a core board and a first metal base arranged on the core board, and a first circuit layer is formed on the surface of the core board; Covering the pre-processed circuit board with a thickening layer and laminating the thickening layer, wherein the thickening layer includes a third metal layer and a dielectric layer, and the dielectric layer is arranged between the first circuit layer and the third metal layer; forming a second metal base on the first metal base; Patterning the third metal layer to form a second circuit layer; Wherein, the step of covering the thickening layer on the pre-treated circuit board and laminating it specifically includes: Acquire the third metal layer; Disposing the dielectric layer on at least one surface of the third metal layer; forming a groove on the dielectric layer so that a portion of the surface of the third metal layer is exposed through the groove to obtain a thickened layer; The surface of the thickened layer provided with the groove faces the pre-treated circuit board, so that the groove accommodates the exposed end of the first metal base; applying pressure to the thickened layer; The step of forming a second metal base on the first metal base includes: removing the third metal layer in contact with the end surface of the first metal base to form a window, through which the first metal base is exposed; In the step of applying pressure to the thickened layer, the third metal layer is in contact with the end surface of the first metal base.

2. The method for manufacturing a circuit board according to claim 1, characterized in that: The step of obtaining the pre-processed circuit board specifically includes: Obtaining a core board, the core board comprising a substrate and a first metal layer and a second metal layer disposed on two opposite surfaces of the substrate; forming a connection hole on the surface of the core board provided with the first metal layer, so that the second metal layer is exposed through the connection hole; Covering the first metal layer with a first photosensitive resist layer on the surface other than the surface where the connecting hole is provided; forming the first metal matrix in the connection hole; The first photosensitive resist layer is removed, and the surface of the first metal layer is patterned to form a first circuit layer.

3. The method for manufacturing a circuit board according to claim 2, characterized in that: The surface of the first metal base is higher than the first circuit layer.

4. The method for manufacturing a circuit board according to claim 1, characterized in that: The step of forming the second metal base on the first metal base specifically includes: Covering the other third metal layers except the window with a second photosensitive resist; forming the second metal matrix in the window; The step of patterning the third metal layer to form a second circuit layer comprises: removing the second photosensitive resist layer; The third metal layer is formed into the second circuit layer by wet chemical etching.

5. The method for manufacturing a circuit board according to claim 1, characterized in that: The step of patterning the third metal layer to form a second circuit layer specifically includes: The third metal layer is etched by wet chemical method to form a second circuit layer, so that the end surface of the first metal base is exposed through the gap between the second circuit layers; The step of forming the second metal base on the first metal base specifically includes: Covering the gap between the second circuit layer and the other second circuit layers except the exposed first metal base with a second photosensitive resist layer, so that a window is formed on the second photosensitive resist layer, and the first metal base is exposed through the window; forming the second metal matrix in the window; The second photoresist layer is removed.

6. The method for manufacturing a circuit board according to claim 1, characterized in that: The width of the groove is greater than the width of the exposed end of the first metal base, and the difference between the width of the groove and the width of the first metal base is 10 micrometers to 200 micrometers.

7. The method for manufacturing a circuit board according to claim 2, characterized in that: The first metal layer and the second metal layer are copper foils.

8. A circuit board, characterized in that: The circuit board is manufactured by the circuit board manufacturing method according to any one of claims 1 to 7.

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