Board-to-board connecting structure and manufacturing method thereof

Abstract

The invention discloses a board-to-board connection structure and a manufacturing method thereof, the board-to-board connection structure comprises a first circuit board, a second circuit board, a first packaging layer and a rewiring layer, the first circuit board comprises a first surface and a second surface which are oppositely arranged, and the first surface is provided with a first connection pad; the second circuit board comprises a third surface and a fourth surface which are oppositely arranged, a second connecting pad is arranged on the third surface, the second circuit board and the first circuit board are arranged side by side, and the first packaging layer is located on the first surface and the third surface and wraps the first connecting pad and the second connecting pad; the rewiring layer is located on the surface of the first packaging layer and electrically connected with the first connecting pad and the second connecting pad, so that the first circuit board is electrically connected with the second circuit board. The board-to-board connection structure is simple in connection mode, convenient to operate and free of deviation, fine-pitch high-density connection can be achieved, the thickness of a connection area can be effectively reduced, and the board-to-board connection structure is beneficial to light, thin, short and small development of products.

Description

Technical Field

[0001] The present application relates to the technical field of printed circuit boards, and in particular to a board-to-board connection structure and a manufacturing method thereof. Background Art

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

[0003] At present, the connection between circuit boards (such as flexible boards and rigid boards) usually requires the use of connectors or hot bar soldering (HotBar) processes. However, when the above solutions are used to connect two circuit boards, there is a problem of offset between the circuit boards, and high-density connection cannot be achieved; at the same time, the thickness of the connected product is thick, the volume is large, and the space occupied is large. In addition, other parts cannot be installed on the back of the connection, and the space utilization rate is low, which is not conducive to the development of electronic products towards thinness and miniaturization. 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 board-to-board connection structure.

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

[0006] The present application provides a board-to-board connection structure, which includes a first circuit board, a second circuit board, a first packaging layer and a redistribution layer, the first circuit board includes a first surface and a second surface arranged 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 arranged 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, and the fourth surface and the second surface are located on the same side; the first packaging 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 packaging 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 a metal wiring electrically connected to the surface of the first conductor and the second conductor, the first packaging layer includes a patterned groove, and a first through hole and a second through hole arranged through the first packaging layer, the patterned groove connects the first through hole and the second through hole, the first conductor is located in the first through hole and is electrically connected to the first connection pad, the second conductor is located in the second through hole and is electrically connected to the second connection pad, and the metal wiring is located in the patterned groove.

[0008] In some possible embodiments, along the extension direction of the board-to-board connection structure, the distance between two adjacent first connection pads is at least 50 μm, and the distance between two adjacent second connection pads is at least 50 μm.

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

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

[0011] In some possible embodiments, a first electronic component is further disposed on the first surface and / or the third surface, and the first packaging layer further covers the first electronic component.

[0012] In some possible embodiments, 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.

[0013] In some possible embodiments, a groove is provided on the first packaging layer, and an opening of the groove is located on a surface of the first packaging layer facing away from the first circuit board or the second circuit board.

[0014] In some possible embodiments, a filler is provided in the groove, and the filler is used to reduce the stress generated by the plate-to-plate connection structure after bending.

[0015] The embodiment of the present application also provides a method for manufacturing a board-to-board connection structure, comprising:

[0016] The first circuit board and the second circuit board are arranged side by side, the first circuit board comprises a first surface and a second surface arranged opposite to each other, a first connection pad is arranged on the first surface, the second circuit board comprises a third surface and a fourth surface arranged opposite to each other, a second connection pad is arranged on the third surface, the second circuit board and the first circuit board are arranged side by side, the third surface and the first surface are located on the same side, and the fourth surface and the second surface are located on the same side;

[0017] forming a first packaging layer on the first surface and the third surface, wherein the first packaging layer covers the first connection pad and the second connection pad; and

[0018] A redistribution layer is formed on the surface of the first packaging layer, and the redistribution layer is electrically connected to the first connection pad and the second connection pad respectively, so as to obtain the board-to-board connection structure.

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

[0020] Forming a patterned groove on the first packaging layer, and penetrating the first packaging layer to form a first through hole and a second through hole, wherein the patterned groove communicates with the corresponding first through hole and the second through hole, the first connection pad is exposed in the first through hole, and the second connection pad is exposed in the second through hole; and

[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 groove. The metal wiring, the first conductor and the second conductor constitute the redistribution layer.

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

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

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

[0025] In some possible embodiments, before the step of placing 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 packaging layer, the manufacturing 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 a first encapsulation layer on the first surface and the third surface, the manufacturing method further includes:

[0030] A groove is formed on the first packaging layer, wherein an opening of the groove is located on a surface of the first packaging layer away from the first circuit board or the second circuit board.

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

[0032] A filler is arranged in the groove.

[0033] The board-to-board connection structure provided by the present application connects the first circuit board and the second circuit board together through the first packaging layer, and realizes electrical conduction between the first circuit board and the second circuit board through the redistribution layer, thereby realizing board-to-board connection of at least two circuit boards, without the need for welding process, and the connection method is simple and easy to operate; there is no need to consider the alignment accuracy of the first connection pad and the second connection pad, which reduces the connection difficulty and has no offset problem; the size of the first connection pad and the second connection pad can be freely designed, and a small pad design can be realized, and the distance between two adjacent first connection pads and two adjacent second connection pads can be effectively reduced (the minimum spacing can be 50μm), realizing a fine pitch design, and thus enabling high-density connection; through the redistribution layer To achieve electrical connection, the thickness of the redistribution layer can be made very thin, which effectively reduces the overall thickness of the board-to-board connection structure, and does not require installation space. The distance between the boards can be very small or even non-existent, which is conducive to reducing the size of the board-to-board connection structure, and is convenient for flexible design of the spatial layout of the circuit board, improving space utilization, and is conducive to the development of products towards lightness, thinness and miniaturization; the first packaging layer can also increase the connection strength between the first circuit board and the second circuit board, enhance the strength of the overall board-to-board connection structure, and can protect the first electronic components, and enhance the reliability and stability of the board-to-board connection structure; the second electronic components can also be arranged on the back side opposite to the first connection pad and the second connection pad to increase the arrangement density of the board-to-board connection structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A top view of a board-to-board connection structure provided in one embodiment of the present application.

[0035] Figure 2A schematic cross-sectional structure diagram of a board-to-board connection structure provided in one embodiment of the present application.

[0036] Figure 3 A schematic cross-sectional structure diagram of a board-to-board connection structure provided in another embodiment of the present application.

[0037] Figure 4 A schematic cross-sectional structure diagram of a board-to-board connection structure provided in yet another embodiment of the present application.

[0038] Figure 5 A flowchart for manufacturing a board-to-board connection structure provided in one embodiment of the present application.

[0039] Figure 6 A schematic diagram of the cross-sectional structure of a first circuit board provided in one embodiment of the present application.

[0040] Figure 7 For Figure 6 A structural schematic diagram of a first electronic component disposed on a first circuit board is provided.

[0041] Fig. 8A A schematic diagram of the cross-sectional structure of a second circuit board provided in one embodiment of the present application.

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

[0043] Fig. 9A For Fig. 8A A schematic structural diagram of a first electronic component being arranged on a second circuit board is provided.

[0044] Fig. 9B for Fig. 9A A top view of a first circuit board is provided.

[0045] Fig. 10A For the general Figure 7 The first circuit board and Fig. 9A A schematic cross-sectional structure diagram of the second circuit boards arranged side by side in the positioning fixture.

[0046] Fig. 10B for Fig. 10A Top view of the .

[0047] Fig.11A For Fig. 10A A schematic cross-sectional structural diagram of a first packaging layer being arranged on surfaces of a first circuit board and a second circuit board.

[0048] Fig. 11B for Fig.11A Top view of the .

[0049] Fig. 12A For Fig.11AA schematic cross-sectional structure diagram of a first through hole, a second through hole and a patterned groove formed on a first packaging layer is shown.

[0050] Fig. 12B for Fig.11A Top view of the .

[0051] Fig.13A For Fig. 12A A schematic cross-sectional structure diagram of a redistribution layer formed in the first through hole, the second through hole and the patterned groove.

[0052] Fig. 13B for Fig.13A Top view of the .

[0053] Fig.14A For Fig.13A A schematic cross-sectional structural diagram of a second packaging layer formed on the first packaging layer and the redistribution layer in FIG.

[0054] Fig. 14B for Fig.14A Top view of the .

[0055] Fig.15A For Fig.14A A schematic cross-sectional structure diagram of a second electronic component being arranged on the back side of the first circuit board and the second circuit board.

[0056] Fig. 15B for Fig.15A Top view of the .

[0057] Fig.16 For Fig.11A A schematic cross-sectional structure diagram of forming a first through hole, a second through hole, a patterned groove and a groove on the first packaging layer.

[0058] Fig.17 exist Fig.16 A cross-sectional structural schematic diagram of forming a redistribution layer in the first through hole, the second through hole and the patterned groove, and arranging a filler in the groove.

[0059] Fig.18 It is a schematic diagram of the structure of a planar conductive layer in the prior art.

[0060] Fig.19 and Fig. 20 A schematic structural diagram of forming a patterned groove on a first packaging layer and forming a redistribution layer according to an embodiment of the present application.

[0061] Fig.21 A schematic structural diagram of forming a patterned groove on a first packaging layer according to another embodiment of the present application.

[0062] Fig.22A This is a design form of a patterned groove provided in an embodiment of the present application.

[0063] Fig. 22B for Fig.22A Schematic diagram of the cross-sectional structure.

[0064] Fig.23 This is a design form of a patterned groove provided in another embodiment of the present application.

[0065] Fig.24 A design form of a patterned groove is provided in yet another embodiment of the present application.

[0066] Main component symbols

[0067] Board-to-board connection structure 100

[0068] First circuit board 1

[0069] First surface 11

[0070] Second surface 12

[0071] First connection pad 13

[0072] The first circuit layer 14

[0073] The second circuit layer 15

[0074] Second circuit board 2

[0075] The third surface 21

[0076] Fourth surface 22

[0077] Second connection pad 23

[0078] The third circuit layer 24

[0079] Fourth circuit layer 25

[0080] First encapsulation layer 3

[0081] First through hole 31

[0082] The second through hole 32

[0083] Slot 33

[0084] Filling 34

[0085] Patterned groove 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 components 7

[0093] Gap 8

[0094] First connection area A

[0095] Second connection area B

[0096] Connecting Area C

[0097] Non-connected area D

[0098] direction a

[0099] Distance L1

[0100] Thickness L2

[0101] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0102] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0103] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0104] See also Figure 1 and Figure 2 The embodiment of the present application provides a board-to-board connection structure 100, including a first circuit board 1, a second circuit board 2, a first packaging layer 3 and a redistribution layer 4. The first circuit board 1 includes a first surface 11 and a second surface 12 arranged opposite to each other, and a first connection pad 13 is provided on the first surface 11. The second circuit board 2 includes a third surface 21 and a fourth surface 22 arranged opposite to each other, and a second connection pad 23 is provided 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 located on the same side as the first surface 11, and the fourth surface 22 and the second surface 12 are located on the same side. The first packaging 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 packaging layer 3, and the redistribution layer 4 is electrically connected to the first connection pad 13 and the second connection pad 23 respectively, so as to realize the board-to-board connection and electrical conduction of the first circuit board 1 and the second circuit board 2.

[0105] Please refer again Figure 1 and Figure 2 The first circuit board 1 includes a first connection area A, and the 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 at a non-edge area of ​​the first circuit board 1. Specifically, in order 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 connection pad 13 can be flexibly designed, and the distance L1 between two adjacent first connection pads 13 can be very small to achieve fine pitch connection, thereby achieving high-density connection. In this embodiment, along the extension direction a of the board-to-board connection structure 100, the distance L1 between two adjacent first connection pads 13 can be as small as 50 μm.

[0107] In some embodiments, the first circuit board 1 may be a flexible printed circuit (FPC), a printed circuit board (PCB), or an IC carrier board, etc. The first circuit board 1 may include a single layer of circuits or multiple layers of circuits. 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 circuit layer 14 in addition to the first connection pad 13, and the first circuit 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 circuit layer 15, and the second circuit layer 15 can be connected to the first circuit layer 14 by wires.

[0109] Please refer again Figure 1 and Figure 2, the second circuit board 2 includes a second connection area B, and the second connection pad 23 is located in the second connection area B. The second connection area B may be located at the edge of the second circuit board 2 or at the non-edge area of ​​the second circuit board 2. Specifically, in order to facilitate 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 arranged adjacent to each other, and together constitute a connection area C, and the first packaging layer 3 and the redistribution layer 4 are located in the connection area C. It can be understood that the first connection area A and the second connection area B may also be located in the non-edge area of ​​the corresponding circuit board. By constructing the redistribution layer 4, the board-to-board connection and electrical conduction of the first circuit board 1 and the second circuit board 2 along the horizontal direction (i.e., the extension direction a of the board-to-board connection structure 100) can be achieved, which is impossible to achieve with a traditional board-to-board connector.

[0110] In some embodiments, the second circuit board 2 may be a PCB board, an FPC board, or an IC carrier board, etc. The second circuit board 2 may include a single layer of circuits or multiple layers of circuits. 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 circuit layer 24 in addition to the second connection pad 23, and the third circuit 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 circuit layer 25, and the fourth circuit layer 25 can be connected to the third circuit layer 24 by wires.

[0112] In some embodiments, the size of the second connection pad 23 can be flexibly designed, and the distance between two adjacent second connection pads 23 can be very small to achieve fine pitch connection, thereby achieving high-density connection. In this embodiment, along the extension direction a of the board-to-board connection structure 100, the minimum distance between two adjacent second connection pads 23 can also 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 achieved through the first packaging layer 3 and the redistribution layer 4. There is no special requirement for the thickness between the two boards. It can adapt to a variety of application scenarios and can minimize the thickness of the overall board-to-board connection structure 100.

[0114] Please refer again Figure 2, the 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 bonding strength between the first encapsulation layer 3 and the first surface 11 and the third surface 21 is relatively large (usually greater than 30N / mm), the connection strength between the first circuit board 1 and the second circuit board 2 can be increased, 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 side walls of the first circuit board 1 and the second circuit board 2 can be in contact with each other under the premise of ensuring electrical insulation, thereby reducing the size of the board-to-board connection structure 100, and there can also be a gap 8 between the side walls 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, thereby improving the insulation between the first circuit board 1 and the second circuit board 2, and at the same time, the strength of the connection area C can be further improved.

[0115] In some embodiments, the material of the first packaging layer 3 can be selected to have an insulating effect. The material of the first packaging layer 3 can be one of the resins such as epoxy resin, prepreg (PP), BT resin, polyphenylene oxide (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, so as to cover the first connection pad 13 and the second connection pad 23 and stably connect the first circuit board 1 and the second circuit board 2. The thickness of the first encapsulation layer 3 is the key to achieving the thinness of the board-to-board connection structure 100. The first encapsulation layer 3 can be designed to be thinner to achieve the thinness 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, and the first connection pad 13 and the second connection pad 23 may be visible inside, so as to facilitate the electrical connection between the redistribution layer 4 and the first connection pad 13 and the second connection pad 23. It is understandable that the first encapsulation layer 3 may also be colored, and the color of the first encapsulation layer 3 may be achieved by adjusting the light transmittance of the material of the first encapsulation layer 3.

[0118] Please refer again Figure 2, the 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 packaging layer 3 and is electrically connected to the first connection pad 13, and the second conductor 42 penetrates the first packaging layer 3 and is electrically connected to the second connection pad 23. In some embodiments, a first through hole 31 and a second through hole 32 are formed through the first packaging layer 3, wherein the first conductor 41 is located in the first through hole 31, and the two ends of the first conductor 41 are electrically connected to the first connection pad 13 and the metal wiring 43 respectively, and the second conductor 42 is located in the second through hole 32, and the two ends of the second conductor 42 are electrically connected to the second connection pad 23 and the metal wiring 43 respectively, thereby achieving electrical conduction between the first circuit board 1 and the second circuit board 2. The use of the redistribution layer 4 to achieve the side-by-side conduction between the first circuit board 1 and the second circuit board 2 can achieve a thin and light board-to-board connection structure 100, making the thickness of the connection area the thinnest, and the redistribution layer 4 can achieve fine pitch and high-density connection between the first connection pad 13 and the second connection pad 23.

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

[0120] In some embodiments, the minimum aperture size of the first through hole 31 and the second through hole 32 can be about 5 μm, so that the size of the first conductor 41 and the second conductor 42 can be reduced, which is beneficial to improve the connection density.

[0121] Please refer again Figure 2 The board-to-board connection structure 100 further includes a second packaging layer 5 located on the surface of the first packaging layer 3 and the redistribution layer 4. The second packaging 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 selected from materials with insulating properties, and the material of the second encapsulation layer 5 can be one of epoxy resin, prepreg (PP), BT resin, polyphenylene oxide (PPO), polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc. The material of the second encapsulation layer 5 can also be 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] See also 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, wherein the first electronic component 6 is located on the first surface 11 and / or the third surface 21. Specifically, the first electronic component 6 is located in a non-connection area D of the first surface 11 and / or the third surface 21, wherein the non-connection area D is located outside the connection area C. The first packaging layer 3 also extends to the non-connection area D and covers the first electronic component 6. The first packaging layer 3 formed by the molding technology can effectively protect the first electronic component 6, prevent mechanical damage and the influence of the external environment on the first electronic component 6, and can also improve the reliability and stability of the board-to-board connection structure 100.

[0125] Please refer 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 of 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, thereby increasing the arrangement density of the board-to-board connection structure 100, so as to improve the space utilization rate of the board-to-board connection structure 100, which is conducive to the thinness and miniaturization of electronic products. It can be 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] See also Figure 4 In some embodiments, a groove 33 is further provided on the first packaging layer 3, and the opening of the groove 33 is located on the surface of the first packaging layer 3 away from the first circuit board 1 and the second circuit board 2. Specifically, the groove 33 can be a stress groove for releasing the stress generated by the board-to-board connection structure 100 when bending, so as to improve the reliability of the board-to-board connection structure 100.

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

[0128] It can be understood that the board-to-board connection structure may also include multiple circuit boards, and the board-to-board connection and electrical conduction of the multiple circuit boards in the horizontal direction may be achieved through the first packaging layer and the redistribution layer.

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

[0130] The board-to-board connection structure 100 provided in the embodiment of the present application connects the first circuit board 1 and the second circuit board 2 together in the horizontal direction through the first packaging layer 3, and realizes electrical conduction 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, and there is no need to consider the alignment accuracy of the first connection pad 13 and the second connection pad 23, which reduces the connection difficulty and has no offset problem; the size of the first connection pad 13 and the second connection pad 23 can be freely designed, and a small pad design can be realized, and the spacing between two adjacent first connection pads 13 and two adjacent second connection pads 23 is small, which can realize a fine spacing design and thus realize a high-density connection; the electrical connection is realized through the redistribution layer 4, and the thickness of the redistribution layer 4 can be very thin, which effectively reduces the overall thickness of the board-to-board connection structure 100, and no installation space is required, The distance between the boards can be very small or even non-existent, which is conducive to reducing the size of the board-to-board connection structure 100, and is convenient for flexible design of the spatial layout of the circuit board, improving space utilization, and is conducive to the lightweight and miniaturization of electronic products; the first packaging layer 3 can also increase the connection strength between the first circuit board 1 and the second circuit board 2, improve the strength of the overall board-to-board connection structure 100, and can protect the first electronic component 6, and improve the reliability and stability of the board-to-board connection structure 100; the second electronic component 7 can also be arranged on the back side of the redistribution layer 4 corresponding to the connection area, so as to increase the arrangement density of the board-to-board connection structure 100, improve the space utilization and multifunctionality of electronic products; in addition, a groove 33 is formed on the surface of the first packaging layer 3, and a stress-reducing filler 34 is filled therein, which can reduce the stress generated by the board-to-board connection structure 100 when bending, so as to further improve the reliability of the board-to-board connection structure 100.

[0131] See also Figure 5 , and refer to Figures 6 to 15BThe embodiment of the present application further 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, and specifically includes the following steps:

[0132] Step S0, such as Figures 6 to 9B As shown, the 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] Among them, 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 non-connection area D corresponding to the first surface 11 and the non-connection area D corresponding to the third surface 21 are both provided with the first electronic component 6, and the number of the first electronic components 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 packaging layer is formed later.

[0134] Step S1, such as Fig. 10A and Fig. 10B As shown, the first circuit board 1 and the second circuit board 2 are arranged side by side, wherein 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 a first connection pad 13 is provided on the first surface 11, and a second connection pad 23 is provided on the third surface 21.

[0135] The first connection pad 13 is located in the first connection area A of the first circuit board 1, the second connection pad 23 is located in the second connection area B of the second circuit board 2, and the first connection area A and the second connection area B are arranged adjacent to each other to form a connection area C. Specifically, the first circuit board 1 and the second circuit board 2 can be fixed on a 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, such as Fig.11A and Fig. 11B As shown, a first packaging layer 3 is formed on the first surface 11 and the third surface 21 , and the first packaging layer 3 covers the first connection pad 13 and the second connection pad 23 .

[0137] Specifically, the first encapsulation layer 3 is formed by a molding process to connect the first circuit board 1 and the second circuit board 2 together. The molding process does not need to consider the alignment accuracy and thickness difference between the first circuit board 1 and the second circuit board 2. The process is simple and easy to operate. The difficulty of board-to-board connection is reduced, and the connection strength is high. The first encapsulation layer 3 formed by the molding process has a high bonding strength with the first circuit board 1 and the second circuit board 2, and the bonding strength is greater than 30N / mm. It can ensure that the thickness of the connection area is reduced while achieving high-strength board-to-board connection. Please refer to the above for the material and specific thickness of the first encapsulation layer 3, which will not be described in detail here.

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

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

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

[0141] The step of forming the redistribution layer 4 in step S3 specifically includes:

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

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

[0144] In step S32, a metal wiring 43 is formed in the patterned groove 35, and a first conductor 41 and a second conductor 42 are formed in 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. In order to achieve electrical conduction between the first connection pad 13 and the corresponding second connection pad 23, the first conductor 41 corresponds to the second conductor 42.

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

[0146] Specifically, a patterned groove 35 can be formed on the surface of the first packaging layer 3 in the connection area C in a patterned manner, and then a first through hole 31 and a second through hole 32 are formed. The patterned groove 35 connects the corresponding first through hole 31 and the second through hole 32. The metal wiring 43 is located in the patterned groove 35 and is connected to the corresponding first conductor 41 and the second conductor 42, so that the metal wiring 43 is embedded in the first packaging 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 packaging layer 3 can be: first, a protective film is coated on the surface of the first packaging layer 3, and then the line pattern of the metal wiring 43 is defined by exposure and development, and then the patterned groove 35, the first through hole 31 and the second through hole 32 are formed by laser or etching, and then the redistribution layer 4 is formed by electroplating technology or pouring conductive paste, and the first conductor 41 and the second conductor 42 can be vertically interconnected, so that the first circuit board 1 and the second circuit board 2 are connected.

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

[0149] Step S4, such as Fig.14A and Fig. 14B As shown, a second encapsulation layer 5 is formed on the surface 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 by a plastic encapsulation process to protect the redistribution layer 4. The material of the second encapsulation layer 5 is as mentioned above, and no further details are given here.

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

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

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

[0153] It can be understood that if the first electronic component 6 and the second electronic component 7 are not required in the board-to-board connection structure 100 , step S0 and step S5 do not need to be performed.

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

[0155] A groove 33 is formed on the first packaging layer 3 , and an opening of the groove 33 is located on a surface of the first packaging layer 3 away from the first circuit board 1 and the second circuit board 2 .

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

[0157] It can be understood that, in the same way, multiple circuit boards that need to be spliced ​​can be connected board-to-board to meet actual needs. The board-to-board connection and electrical conductivity along the horizontal direction adopted in the embodiment of the present application are more convenient for the reasonable spatial layout of multiple circuit boards to improve space utilization.

[0158] like Fig.18 As shown, in the prior art, the conductive layer is formed by patterning the metal layer of the copper-clad substrate, and the surface of the conductive layer is flat. Fig.19 and Fig. 20 As shown, the shape of the patterned groove 35 formed by laser ablation is an inverted trapezoidal structure with a large top and a small bottom, and the inner wall of the patterned groove 35 has a microstructure feature of ablation concave. After electroplating or pouring conductive slurry in the patterned groove 35, the surface of the formed redistribution layer 4 has a convex or concave structural feature, which can improve the bonding force between the redistribution layer 4 and the inner wall of the patterned groove 35. Fig.21 As shown, the patterned groove 35 is manufactured by dry etching process. The patterned groove 35 is vertical and has a sidewall with a partially protruding or concave microstructure, which can improve the adhesion of the redistribution layer 4 on the sidewall of the patterned groove 35.

[0159] In the embodiment of the present application, different functions can be achieved by designing the structure of the patterned groove 35. Fig.22A and Fig. 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 = k△T 0.44 A 0.725 , A is the cross-sectional area of ​​the metal conductive layer in the patterned groove 35. In some other embodiments, Fig.23 As shown, the heat dissipation effect of the product can be improved by designing the patterned groove 35 near the hot spot concentration area. The heat formula is: q = -kA△T / △d, A is the cross-sectional area of ​​the metal conductive layer in the patterned groove 35. In some other embodiments, as Fig.24 As shown, the patterned grooves 35 can be designed around the signal lines to isolate the signal lines, thereby reducing the insertion loss of the product.

[0160] In the manufacturing method of the board-to-board connection structure 100 of the embodiment of the present application, by forming the first packaging layer 3 and the redistribution layer 4 on the first circuit board 1 and the second circuit board 2, the board-to-board connection and electrical conduction of the first circuit board 1 and the second circuit board 2 in the horizontal direction can be achieved, without the need for complex processes such as welding, the process is simple, the connection method is simple, the operation is convenient, and the cost is low. Different circuit boards can be connected according to actual needs to meet the specific space layout between the circuit boards, improve space utilization, and have low requirements for the connection space, and can achieve board-to-board connection in the horizontal direction, which is conducive to reducing the thickness of the connection area C, thereby realizing the lightness, thinness and miniaturization of electronic products. In the process of board-to-board connection, there is no need to consider the alignment accuracy of the first connection pad 13 and the second connection pad 23, there is no offset problem, and the reliability of the electrical connection is improved.

Claims

1. A board-to-board connection structure, characterized in that: include: A first circuit board comprises a first surface and a second surface arranged opposite to each other, wherein a first connection pad is arranged on the first surface; A second circuit board, comprising a third surface and a fourth surface arranged opposite to each other, wherein the third surface is provided with a second connection pad, wherein 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, and the fourth surface and the second surface are located on the same side; A first packaging layer, located on the first surface and the third surface, and covering the first connection pad and the second connection pad; and The redistribution layer is located on the surface of the first packaging 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 board-to-board connection structure according to 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 packaging layer includes a patterned groove, and a first through hole and a second through hole arranged through the first packaging layer, the patterned groove communicates with the first through hole and the second through hole, The first conductor is located in the first through hole and electrically connected to the first connection pad, the second conductor is located in the second through hole and electrically connected to the second connection pad, and the metal wiring is located in the patterned groove.

3. The board-to-board connection structure according to claim 1, characterized in that: Along the extension direction of the board-to-board connection structure, the minimum distance between two adjacent first connection pads is 50 μm, and the minimum distance between two adjacent second connection pads is 50 μm.

4. The board-to-board connection structure according to claim 1, characterized in that: The first circuit board has a first connection area, the first connection pad is located in the first connection area, the second circuit board has a second connection area, the second connection pad is located in the second connection area, the first connection area is located at an edge of the first circuit board, the second connection area is located at an edge of the second circuit board, the first connection area and the second connection area are adjacent to each other and constitute a connection area.

5. The board-to-board connection structure according to claim 1, characterized in that: It also includes a second packaging layer located on the surface of the first packaging layer, and the second packaging layer covers the redistribution layer.

6. The board-to-board connection structure according to claim 1, characterized in that: The first surface and / or the third surface is also provided with a first electronic component, and the first packaging layer also covers the first electronic component.

7. The board-to-board connection structure according to claim 1, characterized in that: The second surface and / or the fourth surface is provided with a second electronic component, and the second electronic component is arranged opposite to the redistribution layer.

8. The board-to-board connection structure according to claim 1, characterized in that: The first packaging layer is provided with a groove, and the opening of the groove is located on a surface of the first packaging layer away from the first circuit board or the second circuit board.

9. The board-to-board connection structure according to claim 8, characterized in that: A filler is arranged in the slot, and the filler is used to reduce the stress generated by the plate-to-plate connection structure after bending.

10. A method for manufacturing a board-to-board connection structure, characterized in that: include: The first circuit board and the second circuit board are arranged side by side, the first circuit board comprises a first surface and a second surface arranged opposite to each other, a first connection pad is arranged on the first surface, the second circuit board comprises a third surface and a fourth surface arranged opposite to each other, a second connection pad is arranged on the third surface, the second circuit board and the first circuit board are arranged side by side, the third surface and the first surface are located on the same side, and the fourth surface and the second surface are located on the same side; forming a first packaging layer on the first surface and the third surface, wherein the first packaging 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 packaging layer, and the redistribution layer is electrically connected to the first connection pad and the second connection pad respectively, so as to obtain the board-to-board connection structure.

11. The method for manufacturing a board-to-board connection structure according to claim 10, characterized in that: The step of forming a redistribution layer on the surface of the first packaging layer comprises: Forming a patterned groove on the first packaging layer, and penetrating the first packaging layer to form a first through hole and a second through hole, wherein the patterned groove communicates with the corresponding first through hole and the second through hole, the first connection pad is exposed in the first through hole, and the second connection pad is exposed in the second through hole; and 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 groove. The metal wiring, the first conductor and the second conductor constitute the redistribution layer.

12. The method for manufacturing a board-to-board connection structure according to claim 11, characterized in that: The first through hole, the second through hole and the patterned groove are formed by laser or etching.

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

14. The method for manufacturing a board-to-board connection structure according to 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 a board-to-board connection structure according to claim 10, characterized in that: After the step of forming a redistribution layer on the surface of the first packaging layer, the manufacturing 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 a board-to-board connection structure according to claim 10, characterized in that: After the step of forming the first encapsulation layer on the first surface and the third surface, the manufacturing method further includes: A groove is formed on the first packaging layer, wherein an opening of the groove is located on a surface of the first packaging layer away from the first circuit board or the second circuit board.

17. The method for manufacturing a board-to-board connection structure according to claim 16, characterized in that: After the step of forming a groove on the first packaging layer, the manufacturing method further includes: A filler is arranged in the slot.

Images