Printed circuit board and preparation method of printed circuit board

Abstract

The embodiment of the invention provides a printed circuit board. The flexible copper-clad assembly is stacked between the first core plate and the second core plate, and in the embodiment of the invention, the flexible copper-clad assembly has the characteristics of good flexibility, bending and folding, so that the printed circuit board can be subjected to three-dimensional wiring, and circuit connection can be realized on different planes and even curved surfaces. The space among the first core plate, the flexible copper-clad assembly and the second core plate can be filled with the first bonding layer and the second bonding layer, a certain buffering or blocking effect is achieved, and the situation that materials in the first core plate and the second core plate are prone to cracking is reduced. And moreover, a copper plating process is replaced by a conductive paste hole plugging process, so that electric connection of all layers can be realized during pressing. Based on the flexible copper-clad assembly, the first bonding layer, the second bonding layer and the conductive paste hole plugging process, the printed circuit board with a multi-layer structure can be formed only through one-time pressing, the manufacturing process can be reduced and simplified, the manufacturing cost can be reduced, and the phenomenon that materials of all layers are degraded and cracked due to multiple times of pressing can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of circuit boards, and in particular to a printed circuit board and a method for preparing the printed circuit board. Background Art

[0002] With the rapid development of the Internet and big data, the demand and use of servers and storage are increasing. As the support for data processing and storage of cloud computing and big data, servers and storage directly determine the stability of the entire system.

[0003] Printed Circuit Board (PCB) is the core of the server, and its design directly determines the performance of the server. The printed circuit board includes multiple circuit layers. During the preparation process, multiple layers are laminated and added. Each additional layer requires drilling, copper plating, and wiring to achieve conduction and circuit functions. This method has a long production process and high cost. Summary of the invention

[0004] The present application provides a printed circuit board and a method for preparing the printed circuit board, so as to solve the problem that the performance of the printed circuit board is reduced due to too many pressing times in the process of preparing the printed circuit board.

[0005] In a first aspect, an embodiment of the present application provides a printed circuit board, comprising a first core board, a flexible copper-clad component, a first adhesive layer, a second adhesive layer, and a second core board. The flexible copper-clad component is stacked between the first core board and the second core board, and the first adhesive layer is bonded between the flexible copper-clad component and the first core board, and the second adhesive layer is bonded between the flexible copper-clad component and the second core board. A first blind hole is provided on the side of the first core board facing the flexible copper-clad component, and a first conductive paste is provided in the first blind hole; a second blind hole is provided on the side of the second core board facing the flexible copper-clad component, and a second conductive paste is provided in the second blind hole; a third blind hole is provided on the flexible copper-clad component, and a third conductive paste is provided in the third blind hole. The third conductive paste is connected between the first conductive paste and the second conductive paste, so that the first core board, the flexible copper-clad component, and the second core board are conductive.

[0006] In some embodiments, the flexible copper clad assembly includes a plurality of flexible copper clad boards, the third conductive paste includes a plurality of third sub-conductive members, and the plurality of flexible copper clad boards are electrically connected to each other through the plurality of third sub-conductive members.

[0007] In some embodiments, a plurality of flexible copper clad laminates are stacked, and a third adhesive layer is disposed between two adjacent flexible copper clad laminates.

[0008] In some embodiments, the first core board further includes a first carrier film, which can be peeled and attached to a side of the first adhesive layer facing the flexible copper clad laminate. And / or, the second core board further includes a second carrier film, which can be peeled and attached to a side of the second adhesive layer facing the flexible copper clad laminate.

[0009] In some embodiments, the first core board further includes a first metal layer, a first insulating layer and a second metal layer, wherein the first insulating layer is disposed between the first metal layer and the second metal layer. The first adhesive layer is disposed on a side of the second metal layer away from the first insulating layer, and the first blind hole penetrates the second metal layer and the first insulating layer.

[0010] In some embodiments, the second core board further includes a third metal layer, a second insulating layer and a fourth metal layer, the second insulating layer is disposed between the third metal layer and the fourth metal layer, the second adhesive layer is disposed on a side of the third metal layer away from the second insulating layer, and the second blind hole penetrates the third metal layer and the second insulating layer.

[0011] In some embodiments, the flexible copper clad laminate includes a first copper layer, a liquid crystal polymer layer and a second copper layer, wherein the liquid crystal polymer layer is disposed between the first copper layer and the second copper layer. A third blind hole penetrates the first copper layer and the liquid crystal polymer layer, and a third sub-conductive member is disposed in the third blind hole.

[0012] In a second aspect, an embodiment of the present application provides a method for preparing a printed circuit board, which is used to prepare a printed circuit board as claimed in any one of the first aspects of the claims, and the preparation method includes: providing a first core board, a flexible copper-clad component, a first adhesive layer, a second adhesive layer, and a second core board. The flexible copper-clad component is stacked between the first core board and the second core board, and the first adhesive layer is bonded to the side of the first core board facing the flexible copper-clad component, and the second adhesive layer is bonded to the side of the second core board facing the flexible copper-clad component. A first blind hole is opened on the side of the first core board facing the flexible copper-clad component, and a first conductive paste is arranged in the first blind hole; a second blind hole is opened on the side of the second core board facing the flexible copper-clad component, and a second conductive paste is arranged in the second blind hole; a third blind hole is opened in the flexible copper-clad component, and a third conductive paste is arranged in the third blind hole. The first core board, the flexible copper-clad component, and the second core board are stacked in sequence, and a printed circuit board is formed by a one-time lamination process.

[0013] In some embodiments, before a first blind hole is formed on a side of the first core board facing the flexible copper-clad component, the preparation method further includes: providing a first carrier film, and applying the first carrier film to a side of the first adhesive layer facing the flexible copper-clad laminate. Before a second blind hole is formed on a side of the second core board facing the flexible copper-clad component, the preparation method further includes: providing a second carrier film, and applying the second carrier film to a side of the second adhesive layer facing the flexible copper-clad laminate. Before a third blind hole is formed on the flexible copper-clad component, the preparation method further includes: providing a third carrier film, and applying the third carrier film to a side of the flexible copper-clad laminate facing the first core board.

[0014] In some embodiments, the first core board is stacked in sequence by a first metal layer, a first insulating layer and a second metal layer. The first metal layer includes any one of copper foil, aluminum foil and silver foil. The second metal layer includes any one of copper foil, aluminum foil and silver foil. The first insulating layer includes a BT material layer or a FR4 material layer.

[0015] Different from the related art, in the embodiment of the present application, the flexible copper-clad component has good flexibility, bendability and foldability, so that the printed circuit board can be three-dimensionally wired to realize circuit connection on different planes or even curved surfaces. The first adhesive layer and the second adhesive layer can be filled between the first core board, the flexible copper-clad component and the second core board, and have a certain buffering or blocking effect to reduce the easy decomposition of the materials in the first core board and the second core board. In addition, the conductive paste plugging process is used instead of the copper plating process, and the electrical connection of each layer can be achieved during lamination. Based on the flexible copper-clad component, the first adhesive layer, the second adhesive layer and the conductive paste plugging process, only one lamination is required in the present application to form a multi-layer printed circuit board, which can simplify the manufacturing process, reduce manufacturing costs, and reduce the deterioration and decomposition of each layer of materials caused by multiple laminations. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0017] Figure 1 It is a schematic diagram of the structure of some printed circuit boards provided in the embodiments of the present application;

[0018] Figure 2 is a schematic diagram of the structure of some first core boards provided in the embodiments of the present application;

[0019] Figure 3 is a schematic diagram of the structure of some first core boards provided in the embodiments of the present application;

[0020] Figure 4 is a schematic diagram of the structure of some first blind holes provided in the embodiments of the present application;

[0021] Figure 5 It is a schematic diagram of the structure of some flexible copper clad laminates provided in the embodiments of the present application;

[0022] Figure 6 is a schematic diagram of the structure of some third blind holes provided in the embodiments of the present application;

[0023] Figure 7 is a schematic structural diagram of some third sub-conductive elements provided in the embodiments of the present application;

[0024] Figure 8 is a schematic diagram of the structure of some second core boards provided in the embodiments of the present application;

[0025] Fig. 9 is a schematic diagram of the structure of some second core boards provided in the embodiments of the present application;

[0026] Fig.10 is a schematic diagram of the structure of some second blind holes provided in the embodiments of the present application;

[0027] Fig.11 is a schematic diagram of the structure of some first conductive pastes provided in the embodiments of the present application;

[0028] Fig.12 is a schematic diagram of the structure of some second conductive pastes provided in the embodiments of the present application;

[0029] Fig.13 It is a schematic diagram of the structure of some flexible copper-clad components provided in the embodiments of the present application;

[0030] Fig.14 is a schematic diagram of the structure of some first core boards provided in the embodiments of the present application;

[0031] Fig.15 is a schematic structural diagram of some first carrier films provided in the embodiments of the present application;

[0032] Fig.16 is a schematic diagram of the structure of some second carrier films provided in the embodiments of the present application;

[0033] Fig.17 is a schematic diagram of the structure of some second core boards provided in the embodiments of the present application;

[0034] Fig.18 It is a schematic diagram of the structure of some flexible copper clad laminates provided in the embodiments of the present application;

[0035] Fig.19 It is a schematic diagram of the structure of some flexible copper clad laminates provided in the embodiments of the present application;

[0036] Fig. 20 It is a flow chart of some methods for preparing printed circuit boards provided in the embodiments of the present application.

[0037] Description of reference numerals:

[0038] 100. Printed circuit board;

[0039] 10. first core board; 11. first bonding layer; 12. first blind hole; 13. first metal layer; 14. first insulating layer; 15. second metal layer; 16. first carrier film;

[0040] 20. flexible copper-clad component; 21. flexible copper-clad board; 211. first copper layer; 212. liquid crystal polymer layer; 213. second copper layer; 22. third blind hole; 23. third carrier film;

[0041] 30. second core board; 31. second adhesive layer; 32. second blind hole; 33. third metal layer; 34. second insulating layer; 35. fourth metal layer; 36. second carrier film;

[0042] 40. a first conductive paste;

[0043] 50. a second conductive paste;

[0044] 60. a third conductive paste; 61. a third sub-conductive member;

[0045] 70. The third adhesive layer. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0047] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "several" and "multiple" is more than two, unless otherwise clearly and specifically defined.

[0048] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: 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.

[0049] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. In addition, the technical features involved in the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.

[0050] In a first aspect, the present application embodiment provides a printed circuit board, please refer to Figure 1The printed circuit board 100 includes a first core board 10, a flexible copper clad component 20, a first adhesive layer 11, a second adhesive layer 31 and a second core board 30. The first core board 10 and the second core board 30 are respectively arranged at two ends of the printed circuit board 100, the flexible copper clad component 20 is arranged between the first core board 10 and the second core board 30, and the first adhesive layer 11 is bonded between the flexible copper clad component 20 and the first core board 10, and the second adhesive layer 31 is bonded between the flexible copper clad component 20 and the second core board 30.

[0051] A first blind hole 12 is provided on the side of the first core board 10 facing the flexible copper clad component 20, and a first conductive paste 40 is disposed inside the first blind hole 12. A second blind hole 32 is provided on the side of the second core board 30 facing the flexible copper clad component 20, and a second conductive paste 50 is disposed inside the second blind hole 32. A third blind hole 22 is provided on the flexible copper clad component 20, and a third conductive paste 60 is disposed inside the third blind hole 22. The third conductive paste 60 is connected between the first conductive paste 40 and the second conductive paste 50, so that the first core board 10, the flexible copper clad component 20 and the second core board 30 are conductively connected.

[0052] The first core board 10 is the main carrier of the circuit in the printed circuit board 100. The wiring and connection of the circuit can be realized by making a circuit pattern on the first core board 10. The first core board 10 is a hard plate material with a certain thickness and mechanical strength, which can provide a solid basic structure for the printed circuit board 100, ensure that the printed circuit board 100 maintains a stable shape under various use environments, and makes the printed circuit board 100 not easy to deform, bend or break.

[0053] For details, please refer to Figure 2 The first core board 10 also includes a first metal layer 13, a first insulating layer 14 and a second metal layer 15, and the first insulating layer 14 is arranged between the first metal layer 13 and the second metal layer 15. The first metal layer 13 and the second metal layer 15 can be used as conductive materials to etch circuit patterns, carry and transmit current and electrical signals, and connect electronic components to enable the circuit to work normally. The first metal layer 13 and the second metal layer 15 are usually copper foils, and can also be aluminum foils, silver foils, etc. For example, for a computer motherboard, when the first metal layer 13 and the second metal layer 15 are copper foils, the circuits on the copper foil layer connect various devices such as processors, memory, and graphics cards together, and can realize the transmission of data and instructions.

[0054] The first insulating layer 14 can provide stable support for the first metal layer 13 and the second metal layer 15, and maintain the shape and strength of the first core board 10. The first insulating layer 14 can isolate different conductive circuits to reduce the phenomenon of short circuits between circuits. The conductive circuits that need to be electrically connected can also be connected through multiple conductive pastes. The first insulating layer 14 can be a BT (Bismaleimide Triazine, bismaleimide triazine resin) material layer, a FR4 (glass fiber epoxy resin) material layer or a polyimide material layer. Preferably, the first insulating layer 14 is a BT material layer.

[0055] In some embodiments, please refer to Figure 1 and Figure 3 The first adhesive layer 11 is disposed on the side of the second metal layer 15 away from the first insulating layer 14, and then combined with Figure 4 , the first blind hole 12 penetrates the second metal layer 15 and the first insulating layer 14. When the second metal layer 15 is a discontinuous structure, for example, the second metal layer 15 is etched with a circuit pattern, the first adhesive layer 11 can fill the discontinuous part of the second metal layer 15. In a single lamination process, the first adhesive layer 11 can bond the second metal layer 15 to the first copper layer 211 in the flexible copper clad board 21, so that the first core board 10, the flexible copper clad assembly 20 and the second core board 30 form a whole.

[0056] For the above-mentioned flexible copper clad component 20, please refer to Figure 1 and Figure 5 The flexible copper clad assembly 20 includes a plurality of flexible copper clad laminates 21. The flexible copper clad laminates 21 are formed by bonding copper foil to both sides of an insulating material through certain process treatment. The flexible copper clad laminates 21 are thin and bendable and are widely used in various electronic products. A plurality of flexible copper clad laminates 21 can be stacked in sequence on the inner layer of a printed circuit board 100. Compared with a commonly used printed circuit board 100, the circuit arrangement of the printed circuit board 100 is enriched by adding a structure of a flexible copper clad laminate 21, and is not limited to a planar structure. The flexible copper clad laminate 21 has good flexibility, bendability and foldability, allowing the circuit board to be three-dimensionally wired to achieve circuit connection on different planes or even curved surfaces.

[0057] In the printed circuit board 100 prepared in the embodiment of the present application, a plurality of flexible copper clad laminates 21 can be provided as needed, and the plurality of flexible copper clad laminates 21 can be stacked in sequence on the inner layer of the printed circuit board 100. Figure 6 and Figure 7The flexible copper clad component 20 is provided with a third blind hole 22, and a third conductive paste 60 may be disposed in the third blind hole 22. The third conductive paste 60 includes a plurality of third sub-conductive members 61, and the plurality of flexible copper clad boards 21 are mutually conductive through the plurality of third sub-conductive members 61. For example, the number of layers of the flexible copper clad board 21 may be one layer, two layers, three layers, four layers, five layers, etc. For example, when the flexible copper clad board 21 is a single layer, the flexible copper clad board 21 is disposed between the first core board 10 and the second core board 30, and a first adhesive layer 11 is disposed on the surface of the first core board 10 facing the flexible copper clad board 21, and a second adhesive layer 31 is disposed on the surface of the second core board 30 facing the flexible copper clad board 21. Since the flexible copper clad board 21 is a single layer, the third conductive paste 60 includes a third sub-conductive member 61.

[0058] For details, please refer to Figures 5 to 7 The flexible copper clad laminate 21 includes a first copper layer 211, a liquid crystal polymer layer 212 and a second copper layer 213, and the liquid crystal polymer layer 212 is arranged between the first copper layer 211 and the second copper layer 213. The third blind hole 22 penetrates the first copper layer 211 and the liquid crystal polymer layer 212, and the third sub-conductor 61 is arranged in the third blind hole 22. The first copper layer 211 and the second copper layer 213 are composed of copper foil. The liquid crystal polymer layer 212 is an insulating layer formed by liquid crystal polymer. Liquid crystal polymer (LCP) is a high-performance special engineering polymer material. The molecular structure of liquid crystal polymer has a high degree of regularity and order. Its molecules are usually composed of rigid aromatic rings and flexible fatty chains. This special structure enables liquid crystal polymer to form a liquid crystal state under certain conditions. Liquid crystal polymer has excellent mechanical properties such as high strength, high modulus and high toughness. Liquid crystal polymers also have excellent heat resistance. Their glass transition temperature is generally above 250°C and their heat deformation temperature can reach above 300°C. This enables liquid crystal polymers to be used for a long time in high temperature environments without any obvious performance degradation.

[0059] For the second core plate 30, please refer to Figure 1 and Figure 8 The second core board 30 has a similar structure and function to the first core board 10. The second core board 30 is also the main carrier of the circuit in the printed circuit board 100. The second core board 30 has a certain thickness and mechanical strength to ensure that the printed circuit board 100 maintains a stable shape under various use environments, so that the printed circuit board 100 is not easily deformed, bent or broken.

[0060] For details, please refer to Figure 8The second core board 30 also includes a third metal layer 33, a second insulating layer 34 and a fourth metal layer 35, and the second insulating layer 34 is arranged between the third metal layer 33 and the fourth metal layer 35. The third metal layer 33 and the fourth metal layer 35 are conductive materials that carry and transmit current and electrical signals, and connect electronic components so that the circuit can work normally. The third metal layer 33 and the fourth metal layer 35 are usually copper foils, or aluminum foils, silver foils, etc. The second insulating layer 34 can provide stable support for the third metal layer 33 and the fourth metal layer 35 to maintain the shape and strength of the second core board 30. The second insulating layer 34 can be a BT material layer, a FR4 material layer or a polyimide material layer.

[0061] In some embodiments, please refer to Figure 1 and Fig. 9 The second adhesive layer 31 is disposed on the side of the third metal layer 33 away from the second insulating layer 34, and then combined with Fig.10 , the second blind hole 32 penetrates the third metal layer 33 and the second insulating layer 34. When the third metal layer 33 is a discontinuous structure, for example, the third metal layer 33 is etched with a circuit pattern, the second adhesive layer 31 can fill the discontinuous part of the third metal layer 33. In a single lamination process, the second adhesive layer 31 can bond the third metal layer 33 to the second copper layer 213 in the flexible copper clad board 21, so that the first core board 10, the flexible copper clad assembly 20 and the second core board 30 form a whole.

[0062] In some embodiments, please refer to Figure 4 and Fig.11 After the first blind hole 12 is formed in the first core board 10, the first conductive paste 40 can be inserted into the first blind hole 12. The first conductive paste 40 can connect the first metal layer 13 and the second metal layer 15. Fig.10 and Fig.12 After the second blind hole 32 is opened in the second core board 30, the second conductive paste 50 can be inserted into the second blind hole 32, and the second conductive paste 50 can connect the third metal layer 33 and the fourth metal layer 35. Figure 6 and Figure 7 After the third blind hole 22 is formed in the flexible copper clad board 21, the third conductive paste 60 can be inserted into the third blind hole 22. Figure 1 The third conductive paste 60 can connect the first copper layer 211 and the second copper layer 213. The number of the first blind holes 12 in the first core board 10, the number of the second blind holes 32 in the second core board 30, and the number of the third blind holes 22 in the flexible copper clad board 21 can be set as needed.

[0063] The first conductive paste 40 is a conductive material with a paste structure, and includes copper paste, silver paste, aluminum paste, graphite conductive paste, carbon black conductive paste, and the like.

[0064] The second conductive paste 50 and the third conductive paste 60 have similar functions to the first conductive paste 40 . Both the first conductive paste 40 and the second conductive paste 50 include copper paste, silver paste, aluminum paste, graphite conductive paste, carbon black conductive paste, and the like.

[0065] Please refer to Figure 1 and Figure 3 , for the above-mentioned first adhesive layer 11. The first adhesive layer 11 includes a prepreg. The prepreg is also called a PP sheet, which is mainly composed of resin and reinforcing material. The prepreg plays a role in bonding the layers of copper foil or substrate in the production process of the multi-layer printed circuit board 100. By heating or pressurizing, the resin in the prepreg softens and flows to fill the tiny pores between the layers, firmly bonding the adjacent copper foils or substrates together to form an integral multi-layer structure. The first adhesive layer 11 also has the function of electrical isolation. Since the resin material in the prepreg has good insulation properties, different conductive lines on the printed circuit board 100 can be isolated, reducing the risk of short circuits between circuits and ensuring the normal operation of electronic equipment.

[0066] Among them, common resin materials in prepreg include epoxy resin, phenolic resin, etc. Reinforcement materials include glass cloth, paper base or composite materials.

[0067] Please refer to Figure 1 and Fig. 9 As for the second adhesive layer 31, similar to the first adhesive layer 11, the second adhesive layer 31 includes a prepreg. When the second adhesive layer 31 is heated or pressurized, the resin in the prepreg softens and flows, and the adjacent copper foils or substrates are firmly bonded together to form an integral multi-layer structure.

[0068] After the first core board 10, the flexible copper-clad component 20 and the second core board 30 are stacked and processed and heated, the first insulating layer 14 in the first core board 10 and the second insulating layer 34 in the second core board 30 have a temperature tolerance range of about 150°C to 200°C. For example, when the first insulating layer 14 and the second insulating layer 34 are FR4, the maximum temperature that the FR4 material can withstand is 180°C, and the temperature tolerance range of the FR4 material is generally between 130°C and 180°C. When the first insulating layer 14 and the second insulating layer 34 are BT materials, the temperature tolerance range of the BT material is between 160°C and 230°C. However, the temperature resistance of the LCP material is generally above 300°C. When the first core board 10, the flexible copper-clad component 20 and the second core board 30 are mixed and heated, it is easy to cause the first insulating layer 14 material and the second insulating layer 34 material to crack. Taking BT material as an example, by setting the first adhesive layer 11 and the second adhesive layer 31, the resin in the prepreg can be filled into the mixed system of BT material and LCP during the heating process, playing the role of bonding and support. The prepreg makes the heat more evenly distributed in the system, reducing the phenomenon of local overheating. And the prepreg has a buffering or barrier effect in the above-mentioned mixed system, thereby reducing the occurrence of BT material cracking at high temperature.

[0069] In some embodiments, please refer to Fig.13 , multiple flexible copper clad laminates 21 are stacked, and a third adhesive layer 70 is also arranged between two adjacent flexible copper clad laminates 21. Similar to the first adhesive layer 11, the third adhesive layer 70 is also composed of a prepreg. Under the action of heating or pressurizing, the third adhesive layer 70 softens and flows the resin in the prepreg, and firmly bonds the adjacent copper foils or flexible copper clad laminates 21 together to form a whole.

[0070] In some embodiments, please refer to Figure 1 and Fig.14 The first core board 10 further includes a first carrier film 16, which can be peeled and pasted on the side of the first adhesive layer 11 facing the flexible copper clad board 21. The first carrier film 16 is a thin film material used to carry, protect or assist other materials or components during the manufacturing process. Figure 4 and Fig.15 The first blind hole 12 is opened from the first carrier film 16 to the first insulating layer 14. The first carrier film 16 can reduce the impact on the first core board 10 and the first adhesive layer 11 during the hole opening process, such as scratches, dust, moisture, etc. Before laminating the first core board 10, the flexible copper clad component 20, and the second core board 30, or after the first conductive paste 40 is set in the first blind hole 12, the first carrier film 16 can be peeled off to expose part of the first conductive paste 40. The first carrier film 16 includes a polyimide (PI) carrier film, a polyethylene terephthalate (PET) carrier film, or a polyethylene (PE) carrier film.

[0071] In some embodiments, please refer to Figure 1 and Fig.16 The second core board 30 further includes a second carrier film 36, which can be peeled and pasted on the side of the second adhesive layer 31 facing the flexible copper clad board 21. The second carrier film 36 is a thin film material used to carry, protect or assist other materials or components during the manufacturing process. Fig.10 and 17 The second blind hole 32 is opened from the second carrier film 36 to the second insulating layer 34. The second carrier film 36 can reduce the impact on the second core board 30 and the second adhesive layer 31 during the hole opening process, such as scratches, dust, moisture, etc. Before laminating the first core board 10, the flexible copper clad component 20, and the second core board 30, or after the second conductive paste 50 is set in the second blind hole 32, the second carrier film 36 can be peeled off to expose part of the second conductive paste 50. The second carrier film 36 includes a polyimide carrier film, a polyethylene terephthalate carrier film, or a polyethylene carrier film.

[0072] In some embodiments, please refer to Figure 1 and Fig.18 The flexible copper-clad laminate 21 further includes a third carrier film 23, which can be peeled off and attached to the side of the first copper layer 211 away from the liquid crystal polymer layer 212; or the third carrier film 23 can be peeled off and attached to the side of the second copper layer 213 away from the liquid crystal polymer layer 212. The third carrier film 23 has a similar function to the first carrier film 16 and the second carrier film 36. Figure 6 and Fig.19 The third blind hole 22 is opened from the third carrier film 23 to the liquid crystal polymer layer 212. The third carrier film 23 can reduce the impact on the flexible copper clad board 21 during the hole opening process, such as scratches, dust, moisture, etc. Before laminating the first core board 10, the flexible copper clad assembly 20, and the second core board 30, or after the third conductive paste 60 is set in the third blind hole 22, the third carrier film 23 can be peeled off to expose part of the third sub-conductive member 61. The third carrier film 23 includes a polyimide carrier film, a polyethylene terephthalate carrier film, or a polyethylene carrier film.

[0073] In the traditional process of preparing the printed circuit board 100, if the printed circuit board 100 with a preset target number of layers is to be achieved, multiple pressings are required, and each pressing requires drilling and copper plating to achieve conduction between the circuits, and the production process is long and the cost is high. Moreover, the material can withstand a limited number of pressings, and as the number of pressings accumulates, the service life of the material decreases, affecting the performance of the printed circuit board 100. In the embodiment of the present application, the first core board 10, the flexible copper-clad component 20 and the second core board 30 can be pressed together to form a multi-layer circuit board by a one-time pressing molding method. The pressed first core board 10, the flexible copper-clad component 20 and the second core board 30 can be connected through the first conductive paste 40, the second conductive paste 50 and the third conductive paste 60, and the pressing process is not limited by the number of layers, which reduces the damage to the core board and the flexible copper-clad board 21 caused by multiple pressings.

[0074] The embodiment of the present application provides a printed circuit board 100, which includes a first core board 10, a flexible copper clad component 20, a first adhesive layer 11, a second adhesive layer 31 and a second core board 30. The flexible copper clad component 20 is stacked between the first core board 10 and the second core board 30. The flexible copper clad component 20 has good flexibility, bendability and foldability, so that the printed circuit board 100 can be three-dimensionally wired to achieve circuit connection on different planes or even curved surfaces. The first adhesive layer 11 and the second adhesive layer 31 can be filled between the first core board 10, the flexible copper clad component 20 and the second core board 30, and have a certain buffering or blocking effect to reduce the situation where the materials in the first core board 10 and the second core board 30 are easy to decompose. In addition, the conductive paste plugging process is used instead of the copper plating process, and the electrical connection of each layer can be achieved during lamination. Based on the flexible copper clad component 20, the first adhesive layer 11, the second adhesive layer 31 and the conductive paste plugging process, only one lamination is required in the present application to form a multi-layer printed circuit board, which can simplify the manufacturing process, reduce manufacturing costs, and reduce the deterioration and cracking of each layer of materials caused by multiple laminations.

[0075] In a second aspect, the present application provides a method for preparing a printed circuit board, which is used to prepare any printed circuit board of the first aspect. Fig. 20 , the preparation method comprises the following steps:

[0076] Step S1: providing a first core board, a flexible copper clad assembly, a first adhesive layer, a second adhesive layer and a second core board.

[0077] Step S2: stacking the flexible copper clad assembly between the first core board and the second core board, and bonding the first adhesive layer to the side of the first core board facing the flexible copper clad assembly, and bonding the second adhesive layer to the side of the second core board facing the flexible copper clad assembly.

[0078] Step S3: Open a first blind hole on the side of the first core board facing the flexible copper clad component, and set the first conductive paste in the first blind hole; open a second blind hole on the side of the second core board facing the flexible copper clad component, and set the second conductive paste in the second blind hole; open a third blind hole in the flexible copper clad component, and set the third conductive paste in the third blind hole.

[0079] Step S4: stacking the first core board, the flexible copper clad assembly and the second core board in sequence to form a printed circuit board through a one-time lamination process.

[0080] In some embodiments, the first adhesive layer comprises a polypropylene prepreg and the second adhesive layer comprises a polypropylene prepreg.

[0081] In some embodiments, the first adhesive layer is attached to the surface of the first core board facing the flexible copper clad laminate at a temperature ranging from 100° C. to 140° C., a pressure ranging from 20 kg to 30 kg, and a laminating time ranging from 100 s to 120 s.

[0082] In some embodiments, the second adhesive layer is attached to the surface of the second core board facing the flexible copper clad laminate at a temperature of 100° C. to 140° C., a pressure of 20 kg to 30 kg, and a laminating time of 100 s to 120 s.

[0083] The one-time lamination process in the embodiment of the present application refers to laminating the multi-layer processed core board and the prepreg together by high temperature and high pressure. The processed core board is usually completed with etching and wiring of the circuit pattern, and the prepreg will undergo a curing reaction when heated and pressurized, and the layers will be tightly bonded together.

[0084] In some embodiments, before a first blind hole is formed on a side of the first core board facing the flexible copper-clad component, the preparation method further includes providing a first carrier film, and affixing the first carrier film to a side of the first adhesive layer facing the flexible copper-clad laminate. Before a second blind hole is formed on a side of the second core board facing the flexible copper-clad component, the preparation method further includes providing a second carrier film, and affixing the second carrier film to a side of the second adhesive layer facing the flexible copper-clad laminate. Before a third blind hole is formed on the flexible copper-clad component, the preparation method further includes providing a third carrier film, and affixing the third carrier film to a side of the flexible copper-clad laminate facing the first core board.

[0085] In the embodiment of the present application, a first blind hole is opened in the first core board with the first carrier film as the starting end by laser drilling, so that the first blind hole passes through the second metal layer and the first insulating layer, and the first conductive paste is set in the first blind hole, and then the first carrier film is torn off. A second blind hole is opened in the second core board with the second carrier film as the starting end, so that the second blind hole passes through the third metal layer and the second insulating layer, and the second conductive paste is set in the second blind hole, and then the second carrier film is torn off. A third blind hole is opened in the flexible copper clad laminate with the third carrier film as the starting end, so that the third blind hole passes through the first copper layer and the liquid crystal polymer layer, and the third conductive paste is set in the third blind hole, and then the third carrier film is torn off.

[0086] The first carrier film, the second carrier film and the third carrier film all include polyimide carrier film, polyethylene terephthalate carrier film or polyethylene carrier film.

[0087] In some embodiments, the first core board is stacked in sequence by a first metal layer, a first insulating layer and a second metal layer. The first metal layer includes any one of copper foil, aluminum foil and silver foil. The second metal layer includes any one of copper foil, aluminum foil and silver foil. The first insulating layer includes a BT material layer or a FR4 material layer.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A printed circuit board, characterized in that: It includes a first core board, a flexible copper-clad component, a first adhesive layer, a second adhesive layer and a second core board; The flexible copper-clad component is stacked between the first core board and the second core board, and the first adhesive layer is bonded between the flexible copper-clad component and the first core board, and the second adhesive layer is bonded between the flexible copper-clad component and the second core board; A first blind hole is formed on a side of the first core board facing the flexible copper-clad component, and a first conductive paste is disposed in the first blind hole; a second blind hole is formed on a side of the second core board facing the flexible copper-clad component, and a second conductive paste is disposed in the second blind hole; a third blind hole is formed on the flexible copper-clad component, and a third conductive paste is disposed in the third blind hole; The third conductive paste is connected between the first conductive paste and the second conductive paste, so that the first core board, the flexible copper clad component and the second core board are conductive.

2. The printed circuit board according to claim 1, characterized in that: The flexible copper-clad assembly includes a plurality of flexible copper-clad boards, the third conductive paste includes a plurality of third sub-conductive members, and the plurality of flexible copper-clad boards are electrically connected to each other through the plurality of third sub-conductive members.

3. The printed circuit board according to claim 2, characterized in that: The multiple flexible copper-clad laminates are stacked, and a third adhesive layer is arranged between two adjacent flexible copper-clad laminates.

4. The printed circuit board according to claim 1, characterized in that: The first core board further comprises a first carrier film, and the first carrier film is peelably attached to a side of the first adhesive layer facing the flexible copper clad laminate; and / or, The second core board further includes a second carrier film, and the second carrier film is peelably attached to a side of the second adhesive layer facing the flexible copper clad laminate.

5. The printed circuit board according to any one of claims 1 to 4, characterized in that: The first core plate further includes a first metal layer, a first insulating layer and a second metal layer, wherein the first insulating layer is disposed between the first metal layer and the second metal layer; The first adhesive layer is disposed on a side of the second metal layer away from the first insulating layer, and the first blind hole penetrates the second metal layer and the first insulating layer.

6. The printed circuit board according to any one of claims 1 to 4, characterized in that: The second core plate further comprises a third metal layer, a second insulating layer and a fourth metal layer, wherein the second insulating layer is disposed between the third metal layer and the fourth metal layer; The second adhesive layer is disposed on a side of the third metal layer away from the second insulating layer, and the second blind hole penetrates the third metal layer and the second insulating layer.

7. The printed circuit board according to claim 3, characterized in that: The flexible copper-clad laminate comprises a first copper layer, a liquid crystal polymer layer and a second copper layer, wherein the liquid crystal polymer layer is arranged between the first copper layer and the second copper layer; The third blind hole penetrates the first copper layer and the liquid crystal polymer layer, and the third sub-conductive member is arranged in the third blind hole.

8. A method for preparing a printed circuit board, characterized in that: For preparing a printed circuit board as claimed in any one of claims 1 to 7, the preparation method comprising: Providing a first core board, a flexible copper-clad component, a first adhesive layer, a second adhesive layer and a second core board; The flexible copper-clad component is stacked between the first core board and the second core board, and the first adhesive layer is bonded to the side of the first core board facing the flexible copper-clad component, and the second adhesive layer is bonded to the side of the second core board facing the flexible copper-clad component; A first blind hole is formed on a side of the first core board facing the flexible copper-clad component, and a first conductive paste is disposed in the first blind hole; a second blind hole is formed on a side of the second core board facing the flexible copper-clad component, and a second conductive paste is disposed in the second blind hole; a third blind hole is formed on the flexible copper-clad component, and a third conductive paste is disposed in the third blind hole; The first core board, the flexible copper-clad assembly and the second core board are stacked in sequence to form a printed circuit board through a one-time lamination process.

9. The preparation method according to claim 8, characterized in that: Before the first blind hole is opened on the side of the first core board facing the flexible copper-clad component, the preparation method further comprises: providing a first carrier film, and attaching the first carrier film to the side of the first adhesive layer facing the flexible copper-clad board; Before the second blind hole is opened on the side of the second core board facing the flexible copper-clad component, the preparation method further comprises: providing a second carrier film, and attaching the second carrier film to the side of the second adhesive layer facing the flexible copper-clad board; Before the third blind hole is opened in the flexible copper-clad component, the preparation method further includes: providing a third carrier film, and attaching the third carrier film to a side of the flexible copper-clad laminate facing the first core board.

10. The preparation method according to claim 8, characterized in that: The first core plate is provided by stacking a first metal layer, a first insulating layer and a second metal layer in sequence; The first metal layer includes any one of copper foil, aluminum foil and silver foil; The second metal layer includes any one of copper foil, aluminum foil and silver foil; The first insulating layer includes a BT material layer or a FR4 material layer.

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