Plate-to-plate connection structure and its manufacturing method

Abstract

A board-to-board connection structure and its manufacturing method are disclosed. The board-to-board connection structure includes a first circuit board, a second circuit board, a first encapsulation layer, and a redistribution layer. The first circuit board includes a first surface and a second surface disposed opposite to each other, and a first connection pad is provided on the first surface. The second circuit board includes a third surface and a fourth surface disposed opposite to each other, and a second connection pad is provided on the third surface. The second circuit board is arranged side by side with the first circuit board. The first encapsulation layer is located on the first surface and the third surface, and covers the first connection pad and the second connection pad. The redistribution layer is located on the surface of the first encapsulation layer and is electrically connected to the first connection pad and the second connection pad, respectively, so that the first circuit board is electrically connected to the second circuit board. The board-to-board connection structure provided by this application has a simple connection method, is convenient to operate, has no misalignment problem, can realize fine-pitch high-density connection, and can effectively reduce the thickness of the connection area, which is conducive to the development of products towards thinner and smaller size.

Description

Technical Field

[0001] This application relates to the field of printed circuit board technology, and more particularly to a board-to-board connection structure and its manufacturing method. Background Technology

[0002] With the widespread use of printed circuit boards in the electronics field, in order to realize the multi-functionality of electronic products, an electronic product usually needs to assemble multiple circuit boards with different functions.

[0003] Currently, connections between circuit boards (such as flexible boards and rigid boards) typically require connectors or hot-bar soldering processes. However, when connecting two circuit boards using these methods, misalignment issues arise, preventing high-density connections. Furthermore, the resulting product is thicker, larger, and occupies more space. Additionally, other components cannot be installed on the back of the connection point, resulting in low space utilization and hindering the development of thinner and smaller electronic products. Summary of the Invention

[0004] In view of this, in order to overcome at least one of the above-mentioned defects, it is necessary to propose a plate-to-plate connection structure.

[0005] In addition, this application also provides a method for manufacturing the above-mentioned plate-to-plate connection structure.

[0006] This application provides a board-to-board connection structure, which includes a first circuit board, a second circuit board, a first encapsulation layer, and a redistribution layer. The first circuit board includes a first surface and a second surface disposed opposite to each other, and a first connection pad is provided on the first surface. The second circuit board includes a third surface and a fourth surface disposed opposite to each other, and a second connection pad is provided on the third surface. The second circuit board is arranged side by side with the first circuit board, and the third surface and the first surface are located on the same side, as are the fourth surface and the second surface. The first encapsulation layer is located on the first surface and the third surface, and covers the first connection pad and the second connection pad. The redistribution layer is located on the surface of the first encapsulation layer, and the redistribution layer is electrically connected to the first connection pad and the second connection pad, respectively, so that the first circuit board is electrically connected to the second circuit board.

[0007] In some possible embodiments, the redistribution layer includes a first conductor, a second conductor, and metal wiring electrically connected to the surfaces of the first conductor and the second conductor. The first encapsulation layer includes a patterned trench and a first via and a second via disposed through the first encapsulation layer. The patterned trench connects the first via and the second via. The first conductor is located in the first via and electrically connected to the first connection pad. The second conductor is located in the second via and electrically connected to the second connection pad. The metal wiring is located in the patterned trench.

[0008] In some possible embodiments, along the extending direction of the plate-to-plate connection structure, the minimum distance between two adjacent first connecting pads is 50 μm, and the minimum distance between two adjacent second connecting pads is 50 μm.

[0009] In some possible embodiments, the first circuit board has a first connection area and a first connection pad is located in the first connection area, the second circuit board has a second connection area and a second connection pad is located in the second connection area, the first connection area is located at the edge of the first circuit board, the second connection area is located at the edge of the second circuit board, the first connection area and the second connection area are arranged adjacent to each other and form a connection area.

[0010] In some possible embodiments, the board-to-board connection structure further includes a second encapsulation layer located on the surface of the first encapsulation layer, the second encapsulation layer covering the redistribution layer.

[0011] In some possible embodiments, the first surface and / or the third surface are further provided with a first electronic component, and the first encapsulation layer further covers the first electronic component.

[0012] In some possible embodiments, the second surface and / or the fourth surface are provided with second electronic components, which are disposed opposite to the redistribution layer.

[0013] In some possible embodiments, the first encapsulation layer has a slot, the opening of which is located on the surface of the first encapsulation layer opposite to the first circuit board or the second circuit board.

[0014] In some possible embodiments, the slot is filled with a filler material used to reduce the stress generated in the plate-to-plate connection structure after bending.

[0015] This application also provides a method for manufacturing a plate-to-plate connection structure, including:

[0016] A first circuit board and a second circuit board are arranged side by side. The first circuit board includes a first surface and a second surface that are arranged opposite to each other. A first connecting pad is provided on the first surface. The second circuit board includes a third surface and a fourth surface that are arranged opposite to each other. A second connecting pad is provided on the third surface. The second circuit board and the first circuit board are arranged side by side, and the third surface and the first surface are located on the same side. The fourth surface and the second surface are located on the same side.

[0017] A first encapsulation layer is formed on the first surface and the third surface, the first encapsulation layer covering the first connection pad and the second connection pad; and

[0018] A redistribution layer is formed on the surface of the first encapsulation layer, and the redistribution layer is electrically connected to the first connection pad and the second connection pad respectively, thereby obtaining the board-to-board connection structure.

[0019] In some possible embodiments, the step of forming a redistribution layer on the surface of the first encapsulation layer includes:

[0020] Patterned trenches are formed on the first encapsulation layer, and first and second through-holes are formed through the first encapsulation layer. The patterned trenches connect the corresponding first and second through-holes. The first connecting pad is exposed in the first through-hole, and the second connecting pad is exposed in the second through-hole.

[0021] A first conductor and a second conductor are formed in the first through hole and the second through hole, respectively, and a metal wiring electrically connecting the first conductor and the second conductor is formed in the patterned trench. The metal wiring, the first conductor, and the second conductor constitute the redistribution layer.

[0022] In some possible embodiments, the first via, the second via, and the patterned trench are formed by laser or etching.

[0023] In some possible embodiments, after the step of forming the first encapsulation layer on the first surface and the third surface, the fabrication method further includes:

[0024] A second encapsulation layer is formed on the surfaces of the first encapsulation layer and the redistribution layer, and the second encapsulation layer covers the redistribution layer.

[0025] In some possible embodiments, prior to the step of arranging the first circuit board and the second circuit board side by side, the manufacturing method further includes:

[0026] A first electronic component is disposed on the first surface and / or the third surface.

[0027] In some possible embodiments, after the step of forming a redistribution layer on the surface of the first encapsulation layer, the fabrication method further includes:

[0028] A second electronic component is disposed on the second surface and / or the fourth surface, and the second electronic component is disposed opposite to the redistribution layer.

[0029] In some possible embodiments, after the step of forming the first encapsulation layer on the first surface and the third surface, the fabrication method further includes:

[0030] A slot is formed on the first encapsulation layer, and the opening of the slot is located on the surface of the first encapsulation layer opposite to the first circuit board or the second circuit board.

[0031] In some possible embodiments, after the step of forming a slot on the first encapsulation layer, the manufacturing method further includes:

[0032] A filler is placed inside the groove.

[0033] The board-to-board connection structure provided in this application connects a first circuit board and a second circuit board together through a first encapsulation layer, and achieves electrical conductivity between the first and second circuit boards through a redistribution layer, thereby realizing board-to-board connection of at least two circuit boards. No soldering process is required, the connection method is simple, and operation is convenient. There is no need to consider the alignment accuracy of the first and second connecting pads, reducing the connection difficulty and eliminating misalignment issues. The dimensions of the first and second connecting pads can be freely designed, enabling small pad designs and effectively reducing the distance between adjacent first and second connecting pads (the minimum spacing can be as low as 50μm), achieving fine-pitch design and thus enabling high-density connections. Through the redistribution layer... By achieving electrical connection, the thickness of the redistribution layer can be made very thin, effectively reducing the overall thickness of the board-to-board connection structure. Furthermore, no installation space is required, and the distance between boards can be very small or even nonexistent, which helps to reduce the size of the board-to-board connection structure. It also facilitates flexible design of the circuit board's spatial layout, improving space utilization and promoting the development of thinner and smaller products. The first encapsulation layer can also increase the connection strength between the first and second circuit boards, enhancing the overall strength of the board-to-board connection structure and protecting the first electronic components, thus improving the reliability and stability of the board-to-board connection structure. Second electronic components can also be placed on the back side opposite to the first and second connection pads, increasing the layout density of the board-to-board connection structure. Attached Figure Description

[0034] Figure 1 This is a top view of a plate-to-plate connection structure provided in an embodiment of this application.

[0035] Figure 2This is a cross-sectional structural diagram of a plate-to-plate connection structure provided in an embodiment of this application.

[0036] Figure 3 This is a cross-sectional structural diagram of a plate-to-plate connection structure provided in another embodiment of this application.

[0037] Figure 4 This is a cross-sectional structural diagram of a plate-to-plate connection structure provided in another embodiment of this application.

[0038] Figure 5 A flowchart illustrating the fabrication process of a plate-to-plate connection structure provided in one embodiment of this application.

[0039] Figure 6 This is a cross-sectional structural diagram of a first circuit board provided in an embodiment of this application.

[0040] Figure 7 In order to be in Figure 6 A schematic diagram of the structure on which the first electronic component is mounted on the first circuit board is provided.

[0041] Figure 8A This is a cross-sectional structural diagram of a second circuit board provided in an embodiment of this application.

[0042] Figure 8B for Figure 8A A top view of the second circuit board provided.

[0043] Figure 9A In order to be in Figure 8A A schematic diagram of the structure on which the first electronic component is mounted on the second circuit board is provided.

[0044] Figure 9B for Figure 9A A top view of the first circuit board provided.

[0045] Figure 10A To be Figure 7 The first circuit board and Figure 9A A cross-sectional view of the second circuit board arranged side by side in the positioning fixture.

[0046] Figure 10B for Figure 10A Top view.

[0047] Figure 11A In order to be in Figure 10A A cross-sectional view of the first and second circuit boards having a first encapsulation layer disposed on their surfaces.

[0048] Figure 11B for Figure 11A Top view.

[0049] Figure 12A In order to be in Figure 11AThe diagram shows a cross-sectional structure of a first through-hole, a second through-hole, and a patterned trench formed on the first encapsulation layer.

[0050] Figure 12B for Figure 11A Top view.

[0051] Figure 13A In order to be in Figure 12A A cross-sectional schematic diagram of the redistribution layer formed in the first through-hole, the second through-hole, and the patterned trench.

[0052] Figure 13B for Figure 13A Top view.

[0053] Figure 14A In order to be in Figure 13A A cross-sectional view of the second encapsulation layer formed on the first encapsulation layer and the redistribution layer.

[0054] Figure 14B for Figure 14A Top view.

[0055] Figure 15A In order to be in Figure 14A A cross-sectional view of the first and second circuit boards in the diagram, showing the second electronic component mounted on the back side.

[0056] Figure 15B for Figure 15A Top view.

[0057] Figure 16 In order to be in Figure 11A A cross-sectional view of the first encapsulation layer in which a first through-hole, a second through-hole, patterned trenches, and slots are formed.

[0058] Figure 17 exist Figure 16 A cross-sectional structural diagram showing a redistribution layer formed in the first through hole, the second through hole, and the patterned trench, with filler material placed in the trench.

[0059] Figure 18 This is a schematic diagram of a planar conductive layer in the prior art.

[0060] Figure 19 and Figure 20 This is a schematic diagram of a structure in which patterned trenches are formed on a first encapsulation layer and a redistribution layer is formed, according to an embodiment of this application.

[0061] Figure 21 This is a schematic diagram of a structure in which patterned trenches are formed on a first encapsulation layer, according to another embodiment of this application.

[0062] Figure 22A This application provides a patterned groove design in one embodiment.

[0063] Figure 22B for Figure 22A A schematic diagram of the cross-sectional structure.

[0064] Figure 23 This is a design form of patterned groove provided in another embodiment of this application.

[0065] Figure 24 This is a patterned groove design provided in yet another embodiment of the present application.

[0066] Explanation of main component symbols

[0067] Plate-to-plate connection structure 100

[0068] First circuit board 1

[0069] First surface 11

[0070] Second surface 12

[0071] First connecting pad 13

[0072] First Line Layer 14

[0073] Second line layer 15

[0074] Second circuit board 2

[0075] Third surface 21

[0076] Fourth surface 22

[0077] Second connecting pad 23

[0078] Third line layer 24

[0079] Fourth line layer 25

[0080] First encapsulation layer 3

[0081] First through hole 31

[0082] Second through hole 32

[0083] Groove 33

[0084] Filler 34

[0085] Patterned grooves 35

[0086] Rewiring layer 4

[0087] First conductor 41

[0088] Second conductor 42

[0089] Metal wiring 43

[0090] Second encapsulation layer 5

[0091] First Electronic Components 6

[0092] Second electronic component 7

[0093] Gap 8

[0094] First connection area A

[0095] Second connection area B

[0096] Connecting region C

[0097] Non-connected region D

[0098] direction a

[0099] Distance from L1

[0100] Thickness L2

[0101] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0102] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0103] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0104] Please see Figure 1 and Figure 2 This application provides a board-to-board connection structure 100, including a first circuit board 1, a second circuit board 2, a first encapsulation layer 3, and a redistribution layer 4. The first circuit board 1 includes a first surface 11 and a second surface 12 disposed opposite to each other, with a first connection pad 13 disposed on the first surface 11. The second circuit board 2 includes a third surface 21 and a fourth surface 22 disposed opposite to each other, with a second connection pad 23 disposed on the third surface 21. The second circuit board 2 is arranged side-by-side with the first circuit board 1, and the third surface 21 is on the same side as the first surface 11, and the fourth surface 22 and the second surface 12 are on the same side. The first encapsulation layer 3 is located on the first surface 11 and the third surface 21, and covers the first connection pad 13 and the second connection pad 23. The redistribution layer 4 is located on the surface of the first encapsulation layer 3, and is electrically connected to the first connection pad 13 and the second connection pad 23, thereby realizing the board-to-board connection and electrical conduction of the first circuit board 1 and the second circuit board 2.

[0105] Please refer to it again. Figure 1 and Figure 2 The first circuit board 1 includes a first connection area A, and a first connection pad 13 is located in the first connection area A. The first connection area A can be located at the edge of the first circuit board 1 or in a non-edge area of ​​the first circuit board 1. Specifically, to facilitate board-to-board connection, the first connection area A is located at the edge of the first circuit board 1.

[0106] In some embodiments, the size of the first connecting pad 13 can be flexibly designed, and the distance L1 between two adjacent first connecting pads 13 can be very small, achieving fine-pitch connections and thus high-density connections. In this embodiment, along the extension direction a of the board-to-board connection structure 100, the minimum distance L1 between two adjacent first connecting pads 13 can be 50 μm.

[0107] In some embodiments, the first circuit board 1 can be a flexible printed circuit (FPC), a printed circuit board (PCB), or an IC carrier board, etc. The first circuit board 1 can contain one layer of circuitry or multiple layers of circuitry. Specifically, the second circuit board 2 is an FPC board.

[0108] In some embodiments, the first surface 11 of the first circuit board 1 includes a first wiring layer 14 in addition to the first connection pad 13, and the first wiring layer 14 is electrically connected to the first connection pad 13. In some embodiments, the second surface 12 of the first circuit board 1 includes a second wiring layer 15, which can be wired to the first wiring layer 14.

[0109] Please refer to it again. Figure 1 and Figure 2The second circuit board 2 includes a second connection area B, and a second connection pad 23 is located in the second connection area B. The second connection area B can be located at the edge of the second circuit board 2 or in a non-edge region of the second circuit board 2. Specifically, for ease of board-to-board connection, the second connection area B is located at the edge of the second circuit board 2. In some embodiments, the first connection area A is located at the edge of the first circuit board 1, and the second connection area B is located at the edge of the second circuit board 2. When the first circuit board 1 and the second circuit board 2 are arranged side-by-side, the first connection area A and the second connection area B are adjacent to each other, together forming a connection area C. The first encapsulation layer 3 and the redistribution layer 4 are located in the connection area C. It is understood that the first connection area A and the second connection area B can also be located in the non-edge region of the corresponding circuit board. By constructing the redistribution layer 4, board-to-board connection and electrical conduction along the horizontal direction (i.e., the extension direction a of the board-to-board connection structure 100) can be achieved between the first circuit board 1 and the second circuit board 2, which is impossible with traditional board-to-board connectors.

[0110] In some embodiments, the second circuit board 2 can be a PCB board, an FPC board, or an IC carrier board, etc. The second circuit board 2 can contain one layer of circuitry or multiple layers of circuitry. Specifically, the second circuit board 2 is an FPC board.

[0111] In some embodiments, the third surface 21 of the second circuit board 2 includes a third wiring layer 24 in addition to the second connection pad 23, and the third wiring layer 24 is electrically connected to the second connection pad 23. In some embodiments, the fourth surface 22 of the second circuit board 2 includes a fourth wiring layer 25, which can be wired to the third wiring layer 24.

[0112] In some embodiments, the size of the second connecting pad 23 can be flexibly designed, and the distance between two adjacent second connecting pads 23 can be very small, achieving fine-pitch connections and thus high-density connections. In this embodiment, along the extension direction a of the board-to-board connection structure 100, the minimum distance between two adjacent second connecting pads 23 can be 50 μm.

[0113] The thickness of the first circuit board 1 and the second circuit board 2 can be the same or different. The board-to-board connection and electrical conduction of the first circuit board 1 and the second circuit board 2 are realized through the first encapsulation layer 3 and the redistribution layer 4. There are no special requirements for the thickness between the two boards, which can adapt to a variety of application scenarios and make the thickness of the overall board-to-board connection structure 100 as thin as possible.

[0114] Please refer to it again. Figure 2The first encapsulation layer 3 is located on the first connection area A and the second connection area B, connecting the first circuit board 1 and the second circuit board 2 together, and covering the first connection pad 13 and the second connection pad 23. The first encapsulation layer 3 can protect the first connection pad 13 and the second connection pad 23, and because the first encapsulation layer 3 has a large adhesive strength to the first surface 11 and the third surface 21 (usually greater than 30 N / mm), it can increase the connection strength between the first circuit board 1 and the second circuit board 2, thereby improving the strength of the board-to-board connection structure 100. When the first circuit board 1 and the second circuit board 2 are arranged side by side, the sidewalls of the first circuit board 1 and the second circuit board 2 can contact each other while ensuring electrical insulation, thereby reducing the size of the board-to-board connection structure 100. There can also be a gap 8 between the sidewalls of the first circuit board 1 and the second circuit board 2, and the first encapsulation layer 3 can also extend into the gap 8 to improve the insulation between the first circuit board 1 and the second circuit board 2, and at the same time improve the strength of the connection area C.

[0115] In some embodiments, the material of the first encapsulation layer 3 may be an insulating material. The material of the first encapsulation layer 3 may be one of the following resins: epoxy resin, prepreg (PP), BT resin, polyphenylene oxyide (PPO), polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN).

[0116] In some embodiments, the thickness of the first encapsulation layer 3 can be flexibly designed according to actual needs, with the aim of covering the first connecting pad 13 and the second connecting pad 23 and stably connecting the first circuit board 1 and the second circuit board 2 together. The thickness of the first encapsulation layer 3 is key to achieving a thinner board-to-board connection structure 100. The first encapsulation layer 3 can be designed to be thinner, thereby reducing the thickness of the connection area C. In some embodiments, the thickness of the first encapsulation layer 3 can be as thin as 20 μm.

[0117] In some embodiments, the first encapsulation layer 3 may be transparent, allowing the internal first connection pad 13 and second connection pad 23 to be visible, facilitating electrical connection between the redistribution layer 4 and the first connection pad 13 and second connection pad 23. Understandably, the first encapsulation layer 3 may also be colored; the color of the first encapsulation layer 3 can be achieved by adjusting the light transmittance of the material.

[0118] Please refer to it again. Figure 2The redistribution layer 4 includes a first conductor 41, a second conductor 42, and a metal wiring 43 electrically connected to the first conductor 41 and the second conductor 42. The first conductor 41 penetrates the first encapsulation layer 3 and is electrically connected to the first connecting pad 13. The second conductor 42 penetrates the first encapsulation layer 3 and is electrically connected to the second connecting pad 23. In some embodiments, a first through-hole 31 and a second through-hole 32 are formed through the first encapsulation layer 3. The first conductor 41 is located within the first through-hole 31, and its two ends are electrically connected to the first connecting pad 13 and the metal wiring 43, respectively. The second conductor 42 is located within the second through-hole 32, and its two ends are electrically connected to the second connecting pad 23 and the metal wiring 43, respectively, thereby achieving electrical conductivity between the first circuit board 1 and the second circuit board 2. By using the redistribution layer 4 to achieve parallel conductivity between the first circuit board 1 and the second circuit board 2, the board-to-board connection structure 100 can be made thinner and lighter, minimizing the thickness of the connection area. Furthermore, the redistribution layer 4 can achieve fine-pitch and high-density connections between the first connecting pad 13 and the second connecting pad 23.

[0119] In some embodiments, the surface of the first encapsulation layer 3 corresponding to the first connection area A and the second connection area B is lower than the surface of the non-connection area corresponding to the first encapsulation layer 3. That is, by forming a patterned groove 35 on the surface of the first encapsulation layer 3 corresponding to the connection area C, the metal wiring 43 is embedded in the first encapsulation layer 3, thereby further reducing the thickness of the overall connection area.

[0120] In some embodiments, the aperture size of the first through hole 31 and the second through hole 32 can be as small as about 5 μm, thereby reducing the size of the first conductor 41 and the second conductor 42, which is beneficial to improving the connection density.

[0121] Please refer to it again. Figure 2 The board-to-board connection structure 100 also includes a second encapsulation layer 5 located on the surfaces of the first encapsulation layer 3 and the redistribution layer 4. The second encapsulation layer 5 is mainly used to cover the redistribution layer 4 to protect the redistribution layer 4 and improve reliability.

[0122] In some embodiments, the material of the second encapsulation layer 5 can be an insulating material. The material of the second encapsulation layer 5 can be one of the following resins: epoxy resin, prepreg (PP), BT resin, polyphenylene ether (PPO), polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). The material of the second encapsulation layer 5 can also be a protective ink.

[0123] In some embodiments, the total thickness L2 of the first encapsulation layer 3 and the second encapsulation layer 5 is approximately 20 μm to 100 μm, so that the board-to-board connection structure 100 has higher connection stability, while protecting the redistribution layer 4 and improving the reliability of the board-to-board connection structure 100.

[0124] Please see Figure 3 In some embodiments, the board-to-board connection structure 100 further includes a first electronic component 6, which is disposed on at least one of the first circuit board 1 and the second circuit board 2. The first electronic component 6 is located on a first surface 11 and / or a third surface 21. Specifically, the first electronic component 6 is located in a non-connection region D of the first surface 11 and / or the third surface 21, wherein the non-connection region D is located outside the connection region C. The first encapsulation layer 3 extends to the non-connection region D and covers the first electronic component 6. The first encapsulation layer 3, formed using molding technology, can effectively protect the first electronic component 6, preventing mechanical damage and the influence of the external environment on the first electronic component 6, while also improving the reliability and stability of the board-to-board connection structure 100.

[0125] Please refer to it again. Figure 3 In some embodiments, the board-to-board connection structure 100 further includes a second electronic component 7, which is disposed on at least one of the first circuit board 1 and the second circuit board 2, wherein the second electronic component 7 is located on the second surface 12 and / or the fourth surface 22. Specifically, the second electronic component 7 is disposed on at least one of the second surface 12 corresponding to the first connection area A and the fourth surface 22 corresponding to the second connection area B. In some embodiments, the second electronic component 7 is disposed opposite to the redistribution layer 4. The connection area C of the board-to-board connection structure 100 in this embodiment has strong rigidity, and the second electronic component 7 can be disposed on the front and back sides corresponding to the first connection pad 13 and the second connection pad 23, increasing the arrangement density of the board-to-board connection structure 100, thereby improving the space utilization of the board-to-board connection structure 100 and facilitating the miniaturization and thinning of electronic products. It is understood that the second electronic component 7 is not limited to being disposed in the connection area C, but can also be disposed in the non-connection area D.

[0126] Please see Figure 4 In some embodiments, the first encapsulation layer 3 is further provided with a slot 33. The opening of the slot 33 is located on the surface of the first encapsulation layer 3 away from the first circuit board 1 and the second circuit board 2. Specifically, the slot 33 can be a stress groove, which is used to release the stress generated when the board-to-board connection structure 100 is bent, so as to improve the reliability of the board-to-board connection structure 100.

[0127] In some embodiments, the slot 33 is provided with a filler 34, which is mainly used to reduce the stress generated after bending of the plate-to-plate connection structure 100. For example, the filler 34 can be a stress-absorbing material. The specific size, number, shape of the slot 33 and the material of the filler can be designed according to the actual product requirements.

[0128] Understandably, a board-to-board connection structure can also include multiple circuit boards. The first encapsulation layer and the redistribution layer can enable board-to-board connection and electrical conduction of multiple circuit boards in the horizontal direction.

[0129] It is also understandable that the first and second circuit boards in the board-to-board connection structure can be connected to each other through only the first encapsulation layer without electrical conduction.

[0130] The board-to-board connection structure 100 provided in this application embodiment connects the first circuit board 1 and the second circuit board 2 together in the horizontal direction through the first encapsulation layer 3, and realizes electrical conductivity between the first circuit board 1 and the second circuit board 2 through the redistribution layer 4, thereby realizing board-to-board connection of at least two circuit boards. The connection method is simple and easy to operate, eliminating the need to consider the alignment accuracy of the first connecting pad 13 and the second connecting pad 23, reducing the connection difficulty, and eliminating misalignment issues. The dimensions of the first connecting pad 13 and the second connecting pad 23 can be freely designed, enabling small pad designs, and the small spacing between two adjacent first connecting pads 13 and two adjacent second connecting pads 23 allows for fine-pitch designs, thereby achieving high-density connections. Electrical connection is achieved through the redistribution layer 4, which can be made very thin, effectively reducing the overall thickness of the board-to-board connection structure 100, and eliminating the need for installation space. The distance between boards can be very small or even non-existent, which helps to reduce the size of the board-to-board connection structure 100 and facilitates flexible design of the circuit board's spatial layout, improving space utilization and contributing to the miniaturization and thinning of electronic products. The first encapsulation layer 3 can also increase the connection strength between the first circuit board 1 and the second circuit board 2, enhancing the overall strength of the board-to-board connection structure 100 and protecting the first electronic component 6, thereby improving the reliability and stability of the board-to-board connection structure 100. Furthermore, a second electronic component 7 can be placed on the back of the redistribution layer 4 in the connection area, increasing the arrangement density of the board-to-board connection structure 100, improving space utilization, and enhancing the multifunctionality of electronic products. In addition, the groove 33 formed on the surface of the first encapsulation layer 3 and filled with stress-reducing filler 34 can reduce the stress generated when the board-to-board connection structure 100 is bent, further improving the reliability of the board-to-board connection structure 100.

[0131] Please see Figure 5 Please refer to both together. Figures 6 to 15BThis application also provides a method for manufacturing a board-to-board connection structure 100, wherein the board-to-board connection structure 100 includes a first electronic component 6 and a second electronic component 7, specifically including the following steps:

[0132] Step S0, as follows Figures 6 to 9B As shown, a first electronic component 6 is mounted on the first surface 11 of the first circuit board 1 and / or the third surface 21 of the second circuit board 2.

[0133] The first electronic component 6 is located in the non-connection area D around the first connection area A corresponding to the first surface 11, and / or, the first electronic component 6 is located in the non-connection area D around the second connection area B corresponding to the third surface 21. Specifically, the first electronic component 6 is provided in both the non-connection area D corresponding to the first surface 11 and the non-connection area D corresponding to the third surface 21. The number of the first electronic component 6 can be designed according to actual needs. First, the first electronic component 6 and other parts are mounted on the first circuit board 1 and the second circuit board 2, so that the first electronic component 6 can be covered when the first encapsulation layer is formed subsequently.

[0134] Step S1, as follows Figure 10A and Figure 10B As shown, the first circuit board 1 and the second circuit board 2 are arranged side by side. The first surface 11 of the first circuit board 1 and the third surface 21 of the second circuit board 2 are located on the same side, the second surface 12 of the first circuit board 1 and the fourth surface 22 of the second circuit board 2 are located on the same side, and the first surface 11 is provided with a first connecting pad 13, and the third surface 21 is provided with a second connecting pad 23.

[0135] The first connecting pad 13 is located in the first connecting area A of the first circuit board 1, and the second connecting pad 23 is located in the second connecting area B of the second circuit board 2. The first connecting area A and the second connecting area B are arranged adjacent to each other and together form the connecting area C. Specifically, the first circuit board 1 and the second circuit board 2 can be fixed on the positioning fixture, which can improve the stability of the first circuit board 1 and the second circuit board 2 during the connection process, so as to facilitate subsequent operations.

[0136] Step S2, as follows Figure 11A and Figure 11B As shown, a first encapsulation layer 3 is formed on the first surface 11 and the third surface 21, and the first encapsulation layer 3 covers the first connecting pad 13 and the second connecting pad 23.

[0137] Specifically, a first encapsulation layer 3 is formed through a molding process to connect the first circuit board 1 and the second circuit board 2 together. The molding process eliminates the need to consider the alignment accuracy of the first circuit board 1 and the second circuit board 2, as well as thickness differences. It is simple, easy to operate, reduces the difficulty of board-to-board connections, and provides high connection strength. The first encapsulation layer 3 formed by the molding process exhibits high adhesion strength to the first circuit board 1 and the second circuit board 2, exceeding 30 N / mm. This allows for a high-strength board-to-board connection while maintaining a reduced thickness in the connection area. The material and specific thickness of the first encapsulation layer 3 are detailed above and will not be elaborated upon here.

[0138] In some embodiments, the first encapsulation layer 3 is located in the connection region C.

[0139] In some embodiments, when the first electronic component 6 is disposed on the first circuit board 1 and / or the second circuit board 2, during the molding process, the first encapsulation layer 3 formed extends to the non-connection area D and covers the first electronic component 6, thereby protecting the first electronic component 6 and improving the reliability of the product.

[0140] Step S3, as follows Figures 12A to 13B As shown, a redistribution layer 4 is formed on the surface of the first encapsulation layer 3, and the redistribution layer 4 is electrically connected to the first connection pad 13 and the second connection pad 23 respectively.

[0141] Specifically, step S3, which involves forming the redistribution layer 4, includes:

[0142] In step S31, a patterned trench 35 is formed on the first encapsulation layer 3, and a first through hole 31 and a second through hole 32 are formed through the first encapsulation layer 3. The first connecting pad 13 is exposed in the first through hole 31, and the second connecting pad 23 is exposed in the second through hole 32.

[0143] In some embodiments, the patterned trench 35, the first through hole 31, and the second through hole 32 can be formed by means of laser or etching.

[0144] In step S32, a metal wiring 43 is formed within the patterned trench 35, and a first conductor 41 and a second conductor 42 are formed within the first through hole 31 and the second through hole 32, respectively. The metal wiring 43 electrically connects the first conductor 41 and the second conductor 42, thereby forming a redistribution layer 4. Specifically, to achieve electrical conductivity between the first connecting pad 13 and the corresponding second connecting pad 23, the first conductor 41 and the second conductor 42 are aligned.

[0145] In some embodiments, the redistribution layer 4 is formed by electroplating or filling with conductive paste.

[0146] Specifically, patterned trenches 35 can be formed on the surface of the first encapsulation layer 3 in the connection area C in a patterned manner, and then first through holes 31 and second through holes 32 can be formed. The patterned trenches 35 connect the corresponding first through holes 31 and second through holes 32. The metal wiring 43 is located in the patterned trenches 35 and connected to the corresponding first conductor 41 and second conductor 42, so that the metal wiring 43 is embedded in the first encapsulation layer 3 to further reduce the thickness of the connection area C.

[0147] The specific method for constructing the redistribution layer 4 on the surface of the first encapsulation layer 3 can be as follows: first, a protective film is coated on the surface of the first encapsulation layer 3, then the circuit pattern of the metal wiring 43 is defined by exposure and development, then patterned trenches 35, first vias 31 and second vias 32 are formed by laser or etching, and then the redistribution layer 4 is formed by electroplating or pouring conductive paste. The first conductor 41 and the second conductor 42 can be vertically interconnected, thereby connecting the first circuit board 1 and the second circuit board 2.

[0148] After forming the redistribution layer 4 in step S3, the fabrication method further includes:

[0149] Step S4, as follows Figure 14A and Figure 14B As shown, a second encapsulation layer 5 is formed on the surfaces of the first encapsulation layer 3 and the redistribution layer 4, and the second encapsulation layer 5 covers the redistribution layer 4. The second encapsulation layer 5 is also formed using a molding process to protect the redistribution layer 4. The material of the second encapsulation layer 5 is described above and will not be repeated here.

[0150] After step S3, the manufacturing method further includes:

[0151] Step S5, as follows Figure 15A and Figure 15B As shown, a second electronic component 7 is mounted on the second surface 12 and / or the fourth surface 22 to obtain the board-to-board connection structure 100.

[0152] In some embodiments, the second electronic component 7 is located in the connection region C and is disposed opposite to the redistribution layer 4. It is understood that the second electronic component 7 may also be disposed in the non-connection region D.

[0153] Understandably, if the first electronic component 6 and the second electronic component 7 are not required in the board-to-board connection structure 100, then steps S0 and S5 can be skipped.

[0154] like Figure 16 and Figure 17 In some other embodiments, during the process of forming the redistribution layer 4 in step S3, the fabrication method may further include the following steps:

[0155] A slot 33 is formed on the first encapsulation layer 3, and the opening of the slot 33 is located on the surface of the first encapsulation layer 3 opposite to the first circuit board 1 and the second circuit board 2.

[0156] A filler 34 is provided in the slot 33, and the filler 34 is used to reduce the stress generated by the plate-to-plate connection structure 100 after bending.

[0157] Understandably, the same method can be used to connect multiple circuit boards that need to be spliced ​​together board to board to meet actual needs. The board-to-board connection and electrical conduction along the horizontal direction adopted in the embodiments of this application are more conducive to the reasonable spatial layout of multiple circuit boards, so as to improve space utilization.

[0158] like Figure 18 As shown, in the prior art, the conductive layer is formed by patterning the metal layer of a copper-clad substrate, resulting in a smooth surface. However, in the embodiments of this application, as... Figure 19 and Figure 20 As shown, the patterned trench 35 formed by laser ablation has an inverted trapezoidal structure that is larger at the top and smaller at the bottom. The inner wall of the patterned trench 35 has ablation-recessed microstructure features. After electroplating or injecting conductive paste into the patterned trench 35, the surface of the resulting redistribution layer 4 will have raised or recessed structural features, which can improve the adhesion between the redistribution layer 4 and the inner wall of the patterned trench 35. Figure 21 As shown, patterned trenches 35 are fabricated using a dry etching process. The patterned trenches 35 are vertical and have microstructures with local protrusions or concavities on their sidewalls, which can improve the adhesion of the redistribution layer 4 to the sidewalls of the patterned trenches 35.

[0159] In this embodiment, different functions can be achieved by designing the structural form of the patterned grooves 35. For example... Figure 22A and Figure 22B As shown, the current overload capacity of the product can be improved by increasing the size of the patterned groove 35. The current formula is: I = kΔT 0.44 A 0.725 A represents the cross-sectional area of ​​the metal conductive layer in the patterned trench 35. In other embodiments, such as... Figure 23 As shown, the heat dissipation effect of the product can be improved by designing the patterned trenches 35 near areas where hot spots are concentrated. The heat dissipation formula is: q = -kAΔT / Δd, where A is the cross-sectional area of ​​the metal conductive layer in the patterned trenches 35. In some other embodiments, such as Figure 24 As shown, the signal traces can also be isolated by designing patterned grooves 35 around the signal lines, thereby reducing insertion loss of the product.

[0160] In the fabrication method of the board-to-board connection structure 100 in this embodiment, by forming a first encapsulation layer 3 and a redistribution layer 4 on the first circuit board 1 and the second circuit board 2, board-to-board connection and electrical conduction in the horizontal direction can be achieved. This eliminates the need for complex processes such as soldering, simplifying the process and connection method, making operation convenient and cost-effective. Different circuit boards can be connected according to actual needs to meet specific spatial layout requirements, improving space utilization. Furthermore, it has lower requirements for connection space and enables horizontal board-to-board connection, which helps reduce the thickness of the connection area C, thereby achieving the miniaturization and thinning of electronic products. During the board-to-board connection process, there is no need to consider the alignment accuracy of the first connecting pad 13 and the second connecting pad 23, eliminating misalignment issues and improving the reliability of the electrical connection.

Claims

1. A plate-to-plate connection structure, characterized in that, include: The first circuit board includes a first surface and a second surface disposed opposite to each other, and a first connecting pad is provided on the first surface; The second circuit board includes a third surface and a fourth surface disposed opposite to each other. A second connecting pad is provided on the third surface. The second circuit board is disposed side by side with the first circuit board, and the third surface and the first surface are located on the same side. The fourth surface and the second surface are located on the same side. A first encapsulation layer is located on the first surface and the third surface, and covers the first connection pad and the second connection pad; and A redistribution layer is located on the surface of the first encapsulation layer, and the redistribution layer is electrically connected to the first connection pad and the second connection pad respectively, so that the first circuit board is electrically connected to the second circuit board.

2. The plate-to-plate connection structure as described in claim 1, characterized in that, The redistribution layer includes a first conductor, a second conductor, and metal wiring electrically connected to the surfaces of the first conductor and the second conductor. The first encapsulation layer includes patterned trenches and a first via and a second via penetrating the first encapsulation layer. The patterned trenches connect the first via and the second via. The first conductor is located in the first through hole and is electrically connected to the first connecting pad, the second conductor is located in the second through hole and is electrically connected to the second connecting pad, and the metal wiring is located in the patterned trench.

3. The plate-to-plate connection structure as described in claim 1, characterized in that, Along the extending direction of the plate-to-plate connection structure, the minimum distance between two adjacent first connecting pads is 50 μm, and the minimum distance between two adjacent second connecting pads is 50 μm.

4. The plate-to-plate connection structure as described in claim 1, characterized in that, The first circuit board has a first connection area, and the first connection pad is located in the first connection area. The second circuit board has a second connection area, and the second connection pad is located in the second connection area. The first connection area is located at the edge of the first circuit board, and the second connection area is located at the edge of the second circuit board. The first connection area and the second connection area are arranged adjacent to each other and form a connection area.

5. The plate-to-plate connection structure as described in claim 1, characterized in that, It also includes a second encapsulation layer located on the surface of the first encapsulation layer, the second encapsulation layer covering the redistribution layer.

6. The plate-to-plate connection structure as described in claim 1, characterized in that, The first surface and / or the third surface are further provided with a first electronic component, and the first encapsulation layer further covers the first electronic component.

7. The plate-to-plate connection structure as described in claim 1, characterized in that, The second surface and / or the fourth surface are provided with a second electronic component, which is disposed opposite to the redistribution layer.

8. The plate-to-plate connection structure as described in claim 1, characterized in that, The first encapsulation layer has a slot, and the opening of the slot is located on the surface of the first encapsulation layer opposite to the first circuit board or the second circuit board.

9. The plate-to-plate connection structure as described in claim 8, characterized in that, The slot is filled with a filler material, which is used to reduce the stress generated by the plate-to-plate connection structure after bending.

10. A method for manufacturing a plate-to-plate connection structure, characterized in that, include: A first circuit board and a second circuit board are arranged side by side. The first circuit board includes a first surface and a second surface that are arranged opposite to each other. A first connecting pad is provided on the first surface. The second circuit board includes a third surface and a fourth surface that are arranged opposite to each other. A second connecting pad is provided on the third surface. The second circuit board and the first circuit board are arranged side by side, and the third surface and the first surface are located on the same side. The fourth surface and the second surface are located on the same side. A first encapsulation layer is formed on the first surface and the third surface, and the first encapsulation layer covers the first connection pad and the second connection pad; as well as A redistribution layer is formed on the surface of the first encapsulation layer, and the redistribution layer is electrically connected to the first connection pad and the second connection pad respectively, thereby obtaining the board-to-board connection structure.

11. The method for manufacturing the plate-to-plate connection structure as described in claim 10, characterized in that, The step of forming a redistribution layer on the surface of the first encapsulation layer includes: Patterned trenches are formed on the first encapsulation layer, and first and second through-holes are formed through the first encapsulation layer. The patterned trenches connect the corresponding first and second through-holes. The first connecting pad is exposed in the first through-hole, and the second connecting pad is exposed in the second through-hole. A first conductor and a second conductor are formed in the first through hole and the second through hole, respectively, and a metal wiring electrically connecting the first conductor and the second conductor is formed in the patterned trench. The metal wiring, the first conductor, and the second conductor constitute the redistribution layer.

12. The method for manufacturing the plate-to-plate connection structure as described in claim 11, characterized in that, The first through hole, the second through hole, and the patterned trench are formed by laser or etching.

13. The method for manufacturing the plate-to-plate connection structure as described in claim 10, characterized in that, After the step of forming a first encapsulation layer on the first surface and the third surface, the manufacturing method further includes: A second encapsulation layer is formed on the surfaces of the first encapsulation layer and the redistribution layer, and the second encapsulation layer covers the redistribution layer.

14. The method for manufacturing the plate-to-plate connection structure as described in claim 10, characterized in that, Before the step of arranging the first circuit board and the second circuit board side by side, the manufacturing method further includes: A first electronic component is disposed on the first surface and / or the third surface.

15. The method for manufacturing the plate-to-plate connection structure as described in claim 10, characterized in that, After the step of forming a redistribution layer on the surface of the first encapsulation layer, the fabrication method further includes: A second electronic component is disposed on the second surface and / or the fourth surface, and the second electronic component is disposed opposite to the redistribution layer.

16. The method for manufacturing the plate-to-plate connection structure as described in claim 10, characterized in that, After the step of forming a first encapsulation layer on the first surface and the third surface, the manufacturing method further includes: A slot is formed on the first encapsulation layer, and the opening of the slot is located on the surface of the first encapsulation layer opposite to the first circuit board or the second circuit board.

17. The method for manufacturing the plate-to-plate connection structure as described in claim 16, characterized in that, After the step of forming a slot on the first encapsulation layer, the manufacturing method further includes: A filler is placed inside the groove.

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