Telescopic circuit board assembly and preparation method thereof

Abstract

The invention discloses a telescopic circuit board assembly and a preparation method thereof. The preparation method comprises the steps that a flexible circuit board is provided, the flexible circuit board comprises a first base layer and an inner side circuit layer which are stacked in the first direction, the flexible circuit board comprises a connection area and a telescopic area which are arranged in the second direction, and the inner side circuit layer in the connection area comprises an electric connection part; the telescopic area is used for deforming to form bending parts which are sequentially connected in the second direction; an outer side circuit board is arranged on the inner side circuit layer, the electric connection part is exposed out of the outer side circuit board, the telescopic area is used for enabling the electric connection part to stretch out and draw back relative to the outer side circuit board in the second direction during deformation and deformation recovery, and the outer side circuit board comprises a second base layer and an outer side circuit layer which are stacked in the first direction; the second base layer is located between the outer side circuit layer and the inner side circuit layer, and a groove is formed in the surface, away from the outer side circuit layer, of the second base layer and used for containing the bending part.

Description

Technical Field

[0001] The present application relates to the field of circuit boards, and in particular to a retractable circuit board assembly and a preparation method thereof. Background Art

[0002] At present, people have higher and higher requirements for display technology. As a subversive display technology, scroll screen technology has gradually attracted people's attention.

[0003] Flexible circuit boards (FPCBs) are widely used in electronic products due to their flexibility. They enable electrical connections between the screen and motherboard of electronic products, enabling signal conduction and screen display control. However, FPCBs are typically not stretchable, making it difficult to control screen expansion and contraction, limiting their application in the rollable screen market. Summary of the Invention

[0004] In view of this, it is necessary to provide a retractable circuit board assembly.

[0005] In addition, the present application also provides a method for preparing the above-mentioned circuit board assembly.

[0006] According to a first aspect of the present application, a method for preparing a retractable circuit board assembly is provided, comprising: providing a flexible circuit board, the flexible circuit board comprising a first base layer and an inner circuit layer stacked in a first direction, the flexible circuit board comprising a connection region and a retractable region arranged in a second direction perpendicular to the first direction, the inner circuit layer in the connection region comprising an electrical connection portion, the retractable region being configured to deform to form curved portions connected sequentially in the second direction; arranging an outer circuit board on the inner circuit layer, with the electrical connection portion exposed from the outer circuit board, the retractable region being configured to cause the electrical connection portion to retract relative to the outer circuit board in the second direction during deformation and deformation recovery, the outer circuit board comprising a second base layer and an outer circuit layer stacked in the first direction, the second base layer being located between the outer circuit layer and the inner circuit layer, a groove being provided on a surface of the second base layer facing away from the outer circuit layer, the groove being configured to accommodate the curved portion.

[0007] In some possible implementations, before providing the outer circuit board, the preparation method further includes: attaching a plurality of magnetic particles to the inner circuit layer within the retractable region. Providing the outer circuit board specifically includes: forming a coil in the outer circuit layer, wherein the groove and the coil are correspondingly arranged in the first direction, and the coil is configured to generate a magnetic field when energized, thereby attracting the magnetic particles to move toward the coil, thereby causing the retractable region to bend to form the curved portion.

[0008] In some possible implementations, before laminating the magnetic particles, the preparation method further includes: laminating a conductive layer on the inner circuit layer in the stretchable region, wherein the magnetic particles are laminating on the conductive layer.

[0009] In some possible implementations, before setting the outer circuit board, the preparation method further includes: forming a through groove in the flexible circuit board, wherein the through groove is at least partially located in the bending portion; and forming a connecting column on the surface of the second base layer facing away from the outer circuit layer, wherein after setting the outer circuit layer, the connecting column can be slidably set in the through groove.

[0010] In some possible implementations, before setting the outer circuit board, the preparation method further includes: forming part of the flexible circuit board into the bent portions connected sequentially in the second direction by heat setting, wherein after setting the outer circuit board, each of the bent portions is correspondingly accommodated in one of the grooves.

[0011] According to a second aspect of the present application, a retractable circuit board assembly is provided, comprising a flexible circuit board and an outer circuit board disposed on the inner circuit layer. The flexible circuit board comprises a first base layer and an inner circuit layer stacked in a first direction, the flexible circuit board comprising a connection region and a retractable region arranged in a second direction perpendicular to the first direction, the inner circuit layer within the connection region comprising an electrical connection portion, the electrical connection portion being exposed to the outer circuit board. The retractable region is configured to deform to form curved portions connected sequentially in the second direction. The retractable region is configured to cause the electrical connection portion to expand and contract relative to the outer circuit board in the second direction during deformation and recovery. The outer circuit board comprises a second base layer and an outer circuit layer stacked in the first direction, the second base layer being located between the outer circuit layer and the inner circuit layer, the second base layer having a surface facing away from the outer circuit layer provided with a groove, the groove being configured to accommodate the curved portion.

[0012] In some possible implementations, the retractable area includes a curved structure, and the curved structure includes the curved portions sequentially connected in the second direction, and each of the curved portions is correspondingly accommodated in the corresponding groove of the outer circuit board.

[0013] In some possible implementations, a through groove is further formed in the flexible circuit board, and the through groove is at least partially located in the bent portion; the outer circuit board also includes a connecting column provided on the surface of the second base layer facing away from the outer circuit layer, and the connecting column can be slidably disposed in the through groove.

[0014] According to a third aspect of the present application, a retractable circuit board assembly is provided, comprising a flexible circuit board and an outer circuit board. The flexible circuit board comprises a first base layer and an inner circuit layer stacked in a first direction. The flexible circuit board comprises a connection region and a retractable region arranged in a second direction perpendicular to the first direction, the inner circuit layer within the connection region comprising an electrical connection portion. The flexible circuit board further comprises a plurality of magnetic particles attached to the inner circuit layer within the retractable region. The outer circuit board is disposed on the inner circuit layer, with the electrical connection portion exposed from the outer circuit board. The outer circuit board comprises a second base layer and an outer circuit layer stacked in the first direction, the second base layer being located between the outer and inner circuit layers. The outer circuit layer comprises a coil, which, when energized, generates a magnetic field, thereby attracting the magnetic particles toward the coil, thereby causing the retractable region to bend, forming curved portions connected in sequence in the second direction.

[0015] In some possible implementations, a groove is provided on a surface of the second base layer facing away from the outer circuit layer, and the groove is used to accommodate the bent portion.

[0016] In some possible implementations, the flexible circuit board further includes a conductive layer, the conductive layer is adhered to the inner circuit layer in the stretchable area, and the magnetic particles are adhered to the conductive layer.

[0017] In some possible implementations, a through groove is further formed in the flexible circuit board, and the through groove is at least partially located in the bent portion; the outer circuit board also includes a connecting column provided on the surface of the second base layer facing away from the outer circuit layer, and the connecting column can be slidably disposed in the through groove.

[0018] In the present application, since the retractable area can be deformed to form curved portions connected in sequence in the second direction, the electrical connection portion is retracted in the second direction compared to the outer circuit board. Therefore, the circuit board assembly achieves a retractable effect, so that the circuit board assembly can be used to connect with the scroll screen and achieve the purpose of stretching or shortening the scroll screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of a first copper-clad substrate provided in one embodiment of the present application.

[0020] Figure 2 For Figure 1 The diagram shows a schematic structural diagram of the first copper-clad substrate after the first conductive portion is formed.

[0021] Figure 3 For etching Figure 2The structure diagram of the metal layer of the first copper clad substrate and the inner circuit layer after formation is shown.

[0022] Figure 4 For Figure 3 The schematic diagram of the structure after the covering layer is formed on the inner circuit layer is shown.

[0023] Figure 5 For Figure 4 The schematic diagram of the structure of the flexible circuit board obtained after forming a protective layer on the inner circuit layer is shown.

[0024] Figure 6 For Figure 5 The schematic diagram of the structure after the conductive cloth is attached to the inner circuit layer is shown.

[0025] Figure 7 For Figure 6 Schematic diagram of the structure after magnetic particles are attached to the conductive cloth shown.

[0026] Figure 8A For Figure 7 The diagram shows the structure of the flexible circuit board after a through groove is opened.

[0027] Figure 8B for Figure 8A A top view of the flexible circuit board at point A.

[0028] Figure 9 This is a schematic structural diagram of a second copper-clad substrate provided in one embodiment of the present application.

[0029] Figure 10 For Figure 9 The schematic diagram of the structure after forming connecting pillars on the second copper clad substrate is shown.

[0030] Figure 11 For Figure 10 The schematic structural diagram of the substrate unit obtained after forming grooves on the second copper-clad substrate is shown.

[0031] Figure 12 For Figure 11 Schematic diagram of the structure after forming the connecting material on the connecting column shown.

[0032] Figure 13 For Figure 12 The diagram shows the structure of the flexible circuit board after the adhesive layer and substrate unit are formed.

[0033] Figure 14 For Figure 13 Schematic diagram of the structure after pressing.

[0034] Figure 15 For Figure 14FIG. 1 is a schematic structural diagram of a substrate unit after a second conductive portion is formed therein.

[0035] Figure 16 For etching Figure 15 The schematic diagram of the structure of the metal layer of the substrate unit after obtaining the outer circuit layer is shown.

[0036] Figure 17 For Figure 16 The schematic diagram of the structure after the cover layer is formed on the outer circuit layer is shown.

[0037] Figure 18 For Figure 17 The schematic diagram of the structure after the outer circuit board is obtained by forming a protective layer on the outer circuit layer is shown.

[0038] Figure 19 To remove Figure 18 The schematic diagram of the structure behind part of the outer circuit board is shown.

[0039] Figure 20 For Figure 19 The schematic diagram of the structure of the circuit board assembly obtained after electronic components are installed on the outer circuit layer shown.

[0040] Figure 21 For Figure 20 A top view of the circuit board assembly at point B.

[0041] Figure 22 For Figure 20 The schematic diagram of the structure of the circuit board assembly after shrinkage is shown.

[0042] Figure 23 A schematic structural diagram of a flexible circuit board provided in another embodiment of the present application.

[0043] Figure 24 for the reason Figure 23 The schematic diagram of the structure of the circuit board assembly prepared by the flexible circuit board shown.

[0044] Description of main component symbols

[0045] Circuit board components 1 and 2

[0046] First copper clad substrate 10

[0047] First metal layer 11

[0048] Second metal layer 12

[0049] First base 13

[0050] First blind hole 14

[0051] First conductive portion 15

[0052] First inner circuit layer 16

[0053] Second inner circuit layer 17

[0054] First covering layer 18

[0055] Second covering layer 19

[0056] Second copper-clad substrate 20

[0057] The third metal layer 21

[0058] Second base 22

[0059] Connecting column 23

[0060] Groove 24

[0061] Connecting material 25

[0062] Connecting layer 25'

[0063] Second blind hole 26

[0064] Second conductive portion 27

[0065] The third covering layer 28

[0066] Fourth covering layer 29

[0067] First outer circuit layer 30

[0068] First coil 31

[0069] First connection pad 32

[0070] Second outer circuit layer 40

[0071] Second coil 41

[0072] Second connection pad 42

[0073] Flexible circuit board 100

[0074] Connection area 100a

[0075] Scalable area 100b

[0076] Bend portion 100b 1

[0077] Through slot 101

[0078] Electrical connection portion 160

[0079] First protective layer 161

[0080] First conductive layer 180

[0081] Second conductive layer 190

[0082] Adhesive layer 200

[0083] First outer circuit board 300

[0084] Second protective layer 320

[0085] First electronic component 321

[0086] Second outer circuit board 400

[0087] The third protective layer 420

[0088] Second electronic component 421

[0089] Base unit L

[0090] Magnetic particles P

[0091] Intermediate I

[0092] First direction X

[0093] Second direction Y

[0094] The third direction Z

[0095] Distance W1

[0096] Width W2

[0097] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0098] In order to be able to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth in order to fully understand the present application. The embodiments described are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0099] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes all and any combinations of one or more of the relevant listed items.

[0100] In the various embodiments of the present application, for ease of description and not limitation, the term "connection" used in the patent specification and claims of the present application is not limited to physical or mechanical connections, whether direct or indirect. "Up," "down," "above," "below," "left," "right," etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0101] One embodiment of the present application provides a method for preparing a retractable circuit board assembly 1, comprising the following steps:

[0102] Step S1: Please refer to Figure 1 , providing a first copper clad substrate 10, which includes a first metal layer 11, a first base layer 13 and a second metal layer 12 stacked in sequence in a first direction X.

[0103] In one embodiment, the material of the first base layer 13 is an insulating resin. For example, the material of the first base layer 13 can be selected from one of resins such as epoxy resin, polyphenylene oxide (PPO), polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN).

[0104] In some embodiments, the first metal layer 11 and the second metal layer 12 may be made of copper respectively.

[0105] Step S2: Please refer to Figure 2 A first blind hole 14 is formed in the first copper clad substrate 10 , and metal is electroplated in the first blind hole 14 to obtain at least one first conductive portion 15 . The first conductive portion 15 is used to electrically connect the first metal layer 11 and the second metal layer 12 .

[0106] In some embodiments, the first blind via 14 sequentially passes through the first metal layer 11 and the first base layer 13, and the second metal layer 12 serves as the bottom of the first blind via 14. The first conductive portion 15 may be made of copper.

[0107] In some embodiments, the first blind hole 14 can be formed by mechanical drilling or laser drilling.

[0108] Step S3, see Figure 3The first metal layer 11 is etched to obtain a first inner circuit layer 16, and the second metal layer 12 is etched to obtain a second inner circuit layer 17. An electrical connection portion 160 is provided on the first inner circuit layer 16. The electrical connection portion 160 is subsequently used to connect the circuit board assembly 1 to external components (such as the screen or motherboard of an electronic product, not shown).

[0109] In some embodiments, the first metal layer 11 and the second metal layer 12 may be etched by exposure and development.

[0110] In some embodiments, the electrical connection portion 160 may be a gold finger.

[0111] Step S4, see Figure 4 A first covering layer 18 is formed on the first inner circuit layer 16 , and a second covering layer 19 is formed on the second inner circuit layer 17 . The electrical connection portion 160 is exposed from the first covering layer 18 , that is, the first covering layer 18 does not cover the electrical connection portion 160 .

[0112] In some embodiments, each of the first cover layer 18 and the second cover layer 19 may be a cover film (CVL) or a solder resist.

[0113] Step S5, see Figure 5 Surface treatment is performed on the electrical connection portion 160 to form a first protective layer 161, thereby obtaining the flexible circuit board 100. The flexible circuit board 100 includes a connection area 100a and a stretchable area 100b arranged in a second direction Y perpendicular to the first direction X. The first inner circuit layer 16 located within the connection area 100a includes the electrical connection portion 160.

[0114] The first protective layer 161 is used to prevent subsequent surface oxidation of the electrical connection portion 160, which could affect the electrical performance of the electrical connection portion 160. Surface treatment methods may include electroless gold plating, electroless nickel plating, etc. In other embodiments, the first protective layer 161 may also be an organic solder resist (OSP).

[0115] It is understood that this embodiment is described by taking the flexible circuit board 100 as including a first inner circuit layer 16 and a second inner circuit layer 17. In other embodiments, the number of circuit layers included in the flexible circuit board 100 is not limited to two.

[0116] Step S6, see Figure 6 The first conductive layer 180 is laminated on the first covering layer 18 in the stretchable region 100 b , and the second conductive layer 190 is laminated on the second covering layer 19 in the stretchable region 100 b .

[0117] In some embodiments, the first conductive layer 180 and the second conductive layer 190 may be conductive cloths, respectively.

[0118] Step S7, see Figure 7 A plurality of magnetic particles P are respectively attached to the first conductive layer 180 and the second conductive layer 190 .

[0119] In some embodiments, the material of the magnetic particles P can be a magnet, a magnetic metal (such as iron, nickel, cobalt, and alloys thereof), or a ferrite (ie, a magnetic ceramic).

[0120] Step S8, see Figure 8A At least one through-slot 101 is formed in the flexible circuit board 100 , and at least a portion of the through-slot 101 is disposed in the retractable region 100 b .

[0121] Each through groove 101 penetrates the first base layer 13, and in some embodiments, may also penetrate the first cover layer 18 and the second cover layer 19. Figure 8B The first through-groove 101 avoids the first inner circuit layer 16 and the second inner circuit layer 17. In some embodiments, the through-groove 101 can be formed by mechanical drilling or the like.

[0122] Step S9, please refer to Figure 9 , providing a second copper clad substrate 20, which includes a third metal layer 21 and a second base layer 22 stacked in sequence in the first direction X.

[0123] In one embodiment, the material of the second base layer 22 is an insulating resin. For example, the material of the second base layer 22 can be selected from one of the resins such as epoxy resin, polyphenylene oxide (PPO), polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN).

[0124] In some embodiments, the third metal layer 21 may be made of copper.

[0125] Step S10, see Figure 10 At least one connecting column 23 is formed on a surface of the second base layer 22 facing away from the third metal layer 21 .

[0126] In some embodiments, the connection pillars 23 may be formed by electroplating metal, and the material of the connection pillars 23 may be copper. In some embodiments, there may be a plurality of connection pillars 23 .

[0127] Step S11, please refer to Figure 11At least one groove 24 is formed on the surface of the second base layer 22 away from the third metal layer 21. In the second direction Y, the groove 24 is spaced apart from the connecting column 23, that is, the groove 24 is formed in the area of ​​the surface of the second base layer 22 where the connecting column 23 is not provided.

[0128] In some embodiments, the groove 24 can be formed by mechanical drilling or laser drilling. In a cross section parallel to the first direction X and the second direction Y, the groove 24 can be semicircular or square. There can be multiple grooves 24, with the multiple grooves 24 spaced apart in the second direction Y. Furthermore, the groove 24 can be configured so as not to penetrate the entire second base layer 22 in the first direction X.

[0129] Step S12, see Figure 12 , a connecting material 25 is provided at the end of the connecting column 23 away from the second base layer 22 to obtain a substrate unit L.

[0130] In some embodiments, the connection material 25 may be a conductive paste, such as tin paste or copper paste.

[0131] Step S13, please refer to Figure 13 , the substrate unit L, the adhesive layer 200, the flexible circuit board 100, another adhesive layer 200 and another substrate unit L are stacked in sequence so that the connecting column 23 and the groove 24 of each substrate unit L are arranged toward the flexible circuit board 100 to obtain the intermediate I.

[0132] Before lamination, the connection area 100a of the flexible circuit board 100 can be pre-cut to obtain the desired shape. After lamination, the first conductive layer 180 and the second conductive layer 190 of the flexible circuit board 100 are exposed from the corresponding adhesive layer 200, that is, the adhesive layer 200 does not cover the first conductive layer 180 and the second conductive layer 190. The connection area 100a of the flexible circuit board 100 is also exposed from the corresponding adhesive layer 200, that is, the adhesive layer 200 does not cover the connection area 100a.

[0133] At the same time, after lamination, the connection posts 23 of one substrate unit L pass through the through-slots 101 of the flexible circuit board 100 and align with the connection posts 23 of the other substrate unit L. The grooves 24 of the two substrate units L are offset from each other in the second direction Y, and the orthogonal projection of the groove 24 of each substrate unit L on the flexible circuit board 100 is located within the first conductive layer 180 or the second conductive layer 190.

[0134] When each substrate unit L includes multiple connecting posts 23, the distance W1 between the outer side surfaces of the two outermost connecting posts 23 of each substrate unit L in the second direction Y is less than the width W2 of the through-slot 101 of the flexible circuit board 100, allowing subsequent connecting posts 23 to slide within the through-slot 101 along the second direction Y. When each substrate unit L includes only one connecting post 23, the width of the connecting post 23 in the second direction Y is less than the width W2 of the through-slot 101.

[0135] Step S14, please refer to Figure 13 , the intermediate body I is pressed together so that the adhesive layer 200 connects each substrate unit L to the flexible circuit board 100 .

[0136] In some embodiments, heating may be performed during the lamination process to increase the connection strength between the substrate unit L and the flexible circuit board 100 .

[0137] Step S15, please refer to Figure 14 The connection material 25 is solidified to obtain a connection layer 25 ′, and the connection layer 25 ′ fixes the connection posts 23 of different substrate units L.

[0138] In some embodiments, the connection material 25 (eg, solder paste) may be cured by light curing.

[0139] Step S16, see Figure 15 A second blind hole 26 is formed in each substrate unit L, and metal is electroplated in the second blind hole 26 to form at least one second conductive portion 27. The second conductive portion 27 is used to electrically connect the third metal layer 21 to the first inner circuit layer 16 or the second inner circuit layer 17.

[0140] In some embodiments, in the second direction Y, the stretchable region 100b is located between the connecting pillar 23 and the second conductive portion 27. The stretchable region 100b extends out of the adhesive layer 200 in the second direction Y, meaning that the stretchable region 100b is not covered by the adhesive layer 200. A second blind via 26 sequentially passes through the third metal layer 21, the second base layer 22, and the adhesive layer 200. The first inner circuit layer 16 or the second inner circuit layer 17 serves as the bottom of the second blind via 26. The second conductive portion 27 can be made of copper.

[0141] In some embodiments, the second blind hole 26 can be formed by mechanical drilling or laser drilling.

[0142] Step S17, please refer to Figure 16The third metal layer 21 of each substrate unit L is etched to obtain a first outer circuit layer 30 and a second outer circuit layer 40. The first outer circuit layer 30 is located on one side of the first conductive layer 180 and includes at least one first coil 31. The second outer circuit layer 40 is located on one side of the second conductive layer 190 and includes at least one second coil 41.

[0143] In some embodiments, the first outer circuit layer 30 may include multiple first coils 31 , and each first coil 31 is disposed correspondingly to one of the grooves 24 of the corresponding substrate unit L in the first direction X. The second outer circuit layer 40 may include multiple second coils 41 , and each second coil 41 is disposed correspondingly to one of the grooves 24 of the corresponding substrate unit L in the first direction X. The third metal layer 21 may be etched by exposure and development.

[0144] Step S18, please refer to Figure 17 A third cover layer 28 is formed on the first outer wiring layer 30, and a fourth cover layer 29 is formed on the second outer wiring layer 40. A portion of the first outer wiring layer 30 is exposed from the third cover layer 28 to form a first connection pad 32, and a portion of the second outer wiring layer 40 is exposed from the fourth cover layer 29 to form a second connection pad 42.

[0145] In some embodiments, each of the third cover layer 28 and the fourth cover layer 29 may be a cover film (CVL) or a solder resist.

[0146] Step S19, please refer to Figure 18 Surface treatment is performed on the first connection pad 32 to form a second protective layer 320, and surface treatment is performed on the second connection pad 42 to form a third protective layer 420. At this time, the first outer circuit board 300 and the second outer circuit board 400 are respectively obtained on the opposite surfaces of the flexible circuit board 100.

[0147] The second protective layer 320 is used to prevent subsequent surface oxidation of the first connection pad 32, thereby affecting the electrical performance of the first connection pad 32. The third protective layer 420 is used to prevent subsequent surface oxidation of the second connection pad 42, thereby affecting the electrical performance of the second connection pad 42. Surface treatment methods may include chemical gold plating, chemical nickel plating, etc. In other embodiments, the second protective layer 320 or the third protective layer 420 may also be an organic solder resist (OSP).

[0148] It will be appreciated that this embodiment is described using the example of the first outer circuit board 300 including a first outer circuit layer 30 and the second outer circuit board 400 including a second outer circuit layer 40. In other embodiments, the number of circuit layers contained in the first outer circuit board 300 is not limited to one, and the number of circuit layers contained in the second outer circuit board 400 is not limited to one. For example, a circuit layer may be provided on the surface of the first outer circuit board 300 where the groove 24 is provided. For another example, after etching the third metal layer 21 to obtain a circuit layer, additional circuit layers may be further formed on the circuit layer through a build-up process, with the outermost circuit layer being the first outer circuit layer 30. The number of circuit layers contained in the first outer circuit board 300 and the second outer circuit board 400 may be the same or different.

[0149] Step S20, see Figure 19 , first outer circuit board 300 and second outer circuit board 400 located on both sides of connection area 100a of flexible circuit board 100 are removed to expose connection area 100a. Moreover, connection area 100a of flexible circuit board 100 extends out of first outer circuit board 300 and second outer circuit board 400 in second direction Y.

[0150] Step S21, please refer to Figure 20 , the first electronic component 321 is mounted on the first connection pad 32, and the second electronic component 421 is mounted on the second connection pad 42. At this point, the circuit board assembly 1 is obtained.

[0151] in, Figure 21 Show Figure 20 A top view of the circuit board assembly 1 at part A. Figure 21 As shown, the flexible circuit board 100 may have two through slots 101 disposed thereon. The two through slots 101 are spaced apart in a third direction Z that is perpendicular to both the first direction X and the second direction Y. Each through slot 101 is in the shape of an elongated strip extending along the second direction Y. Two connecting posts 23 are slidably disposed within each through slot 101.

[0152] When working, Figure 22As shown, the first outer circuit layer 30 is energized, energizing the first coil 31. Upon energization, the first coil 31 generates a magnetic field, thereby attracting the magnetic particles P on the first conductive layer 180 to move toward the first coil 31. Furthermore, the movement of the magnetic particles P on the first conductive layer 180 drives the corresponding flexible region 100b to move synchronously, causing the portion of the flexible region 100b to bend to form a curved portion 100b1 and be accommodated within the corresponding recess 24 of the first outer circuit board 300. Similarly, the second outer circuit layer 40 is energized, energizing the second coil 41. Upon energization, the second coil 41 generates a magnetic field, thereby attracting the magnetic particles P on the second conductive layer 190 to move toward the second coil 41. Furthermore, the movement of the magnetic particles P on the second conductive layer 190 drives the corresponding flexible region 100b to move synchronously, causing the portion of the flexible region 100b to bend to form a curved portion 100b1 and be accommodated within the corresponding recess 24 of the second outer circuit board 400. At this point, the stretchable region 100b deforms, forming curved portions 100b1 that are sequentially connected in the second direction Y. Adjacent curved portions 100b1 bend in opposite directions. Because different portions of the stretchable region 100b bend in opposite directions, the connection region 100a appears to retract in the second direction Y. Specifically, the length of the connection region 100a extending from the first outer circuit board 300 and the second outer circuit board 400 shortens, or even becomes zero.

[0153] like Figure 20 As shown, when the first and second outer circuit layers 30, 40 are de-energized, and thus the first and second coils 31, 41 are de-energized, the magnetic field disappears, and the stretchable region 100b returns to its original shape. This results in the connection region 100a extending again in the second direction Y, i.e., the length of the connection region 100a extending from the first and second outer circuit boards 300, 400 becomes longer. Therefore, the circuit board assembly 1 of the present application achieves a stretchable effect, allowing it to be connected to a roll-up screen to stretch or shorten the roll-up screen.

[0154] During the aforementioned expansion and contraction process, the connecting post 23 can slide back and forth within the through-slot 101, thereby serving as a guide along the second direction Y. This allows the flexible circuit board 100 to expand and contract along the second direction Y, thanks to the cooperation between the connecting post 23 and the through-slot 101. Furthermore, the first conductive layer 180 and the second conductive layer 190 can each provide electromagnetic shielding, specifically shielding interference signals generated by the first coil 31 and the second coil 41, thereby preventing such interference signals from affecting the normal operation of the first inner circuit layer 16 and the second inner circuit layer 17. In other embodiments, the connecting post 23 and the through-slot 101 can be omitted. The first conductive layer 180 and the second conductive layer 190 can also be omitted.

[0155] It will be appreciated that in some embodiments of the present application, the multiple first coils 31 contained in the first outer circuit layer 30 can be independently controlled, meaning each first coil 31 can be independently energized. Similarly, the multiple second coils 41 contained in the second outer circuit layer 40 can be independently controlled. By controlling the number of energized coils, the number of curved portions 100b1 formed in the flexible circuit board 100 can be controlled. Therefore, the specific length of the flexible circuit board 100 during the extension and retraction process can be adjusted in multiple stages according to actual needs, thereby increasing the degree of flexibility in extension and retraction.

[0156] Another embodiment of the present application further provides a method for preparing a circuit board assembly 2. The method differs from the method of the above embodiment in that, after obtaining the flexible circuit board 100 in step S5, the method comprises the following steps:

[0157] Step S22, see Figure 23 The retractable area 100b is formed into a curved structure by heat setting.

[0158] After forming, the stretchable area 100b includes a plurality of curved portions 100b1 sequentially connected in the second direction Y, and the bending directions of two adjacent curved portions 100b1 are opposite.

[0159] Step S23, please refer to Figure 24 The substrate unit (not shown), adhesive layer 200, flexible circuit board 100, another adhesive layer 200 and another substrate unit are stacked in sequence, so that the multiple bending portions 100b1 of the stretchable area 100b are respectively accommodated in the corresponding grooves 24 of each substrate unit.

[0160] Then, the steps of pressing, curing the connecting material 25, opening the second blind hole 26 and electroplating, etching the third metal layer (not shown), forming the third covering layer 28 and the fourth covering layer 29, surface treatment, removing part of the first outer circuit board 300 and part of the second outer circuit board 400, installing the first electronic component 321 and the second electronic component 421 are carried out in sequence to obtain the circuit board assembly 2.

[0161] In this embodiment, when an external force pulls the connection region 100a of the flexible circuit board 100, the retractable region 100b is stretched under the external force, causing the connection region 100a to further extend in the second direction Y, thereby achieving a stretching effect. When the external force is removed, the retractable region 100b returns to its original state, thereby achieving a retracting effect.

[0162] See also Figure 20One embodiment of the present application also provides a circuit board assembly 1 prepared by the above-mentioned preparation method, comprising a first outer circuit board 300, an adhesive layer 200, a flexible circuit board 100, another adhesive layer 200 and a second outer circuit board 400 stacked in sequence in a first direction X.

[0163] The flexible circuit board 100 includes a first cover layer 18, a first inner circuit layer 16, a first base layer 13, a second inner circuit layer 17, and a second cover layer 19, which are sequentially stacked in a first direction X. The flexible circuit board 100 includes a connection area 100a and a stretchable area 100b arranged in a second direction Y perpendicular to the first direction X. The first inner circuit layer 16 in the connection area 100a includes an electrical connection portion 160, which is exposed to the outer circuit board. The stretchable area 100b is configured to deform to form a bend portion 100b 1 (see FIG. 1 ) that is sequentially connected in the second direction Y. Figure 22 The retractable region 100 b is configured to allow the electrical connection portion 160 to retract in the second direction Y relative to the first outer circuit board 300 and the second outer circuit board 400 during deformation and recovery.

[0164] First outer circuit board 300 includes a second base layer 22 and a first outer circuit layer 30 stacked in a first direction X. Second base layer 22 is located between first outer circuit layer 30 and first inner circuit layer 16. A plurality of grooves 24 may be provided on the surface of second base layer 22 facing away from the outer circuit layers. Second outer circuit board 400 includes another second base layer 22 and a second outer circuit layer 40 stacked in the first direction X. Second base layer 22 is located between second outer circuit layer 40 and second inner circuit layer 17. Each second base layer 22 has a plurality of grooves 24 on the surface facing away from first outer circuit layer 30 or second outer circuit layer 40. Grooves 24 are used to accommodate curved portions 100b1. This embodiment uses an example in which first outer circuit board 300 includes one first outer circuit layer 30 and second outer circuit board 400 includes one second outer circuit layer 40. In other embodiments, the number of circuit layers included in first outer circuit board 300 is not limited to one, and the number of circuit layers included in second outer circuit board 400 is not limited to one. For example, a circuit layer may be provided on the surface of the first outer circuit board 300 where the groove 24 is provided, that is, the first outer circuit board 300 may be a double-sided circuit board. In other embodiments, the groove 24 may also be omitted.

[0165] In some embodiments, the flexible circuit board 100 further includes a first conductive layer 180 attached to the first cover layer 18 and a second conductive layer 190 attached to the second cover layer 19. The first conductive layer 180 and the second cover layer 19 are both disposed corresponding to the stretchable region 100b of the flexible circuit board 100. A plurality of magnetic particles P are attached to each of the first conductive layer 180 and the second conductive layer 190.

[0166] At least one through-slot 101 is formed in the flexible circuit board 100, and at least a portion of the through-slot 101 is located at the bent portion 100b 1. Each through-slot 101 passes through the first cover layer 18, the first inner circuit layer 16, the first base layer 13, the second inner circuit layer 17, and the second cover layer 19.

[0167] The first outer wiring layer 30 is located on one side of the first conductive layer 180 and includes at least one first coil 31 and at least one first connection pad 32. The first connection pad 32 is exposed from the third cover layer 28. Each first coil 31 is arranged corresponding to one of the grooves 24 of the first outer wiring board 300 in the first direction X. At least one connection post 23 is also formed on the surface of the second base layer 22 facing away from the first outer wiring layer 30. The groove 24 is formed in an area of ​​the second base layer 22 where the connection post 23 is not located.

[0168] The second outer wiring layer 40 is located on one side of the second conductive layer 190 and includes at least one second coil 41 and at least one second connection pad 42. The second connection pad 42 is exposed from the fourth cover layer 29. Each second coil 41 is arranged corresponding to one of the grooves 24 of the second outer wiring board 400 in the first direction X. At least one connection post 23 and at least one groove 24 are formed on the surface of the second base layer 22 facing away from the second outer wiring layer 40. The groove 24 is formed in an area of ​​the second base layer 22 where the connection post 23 is not provided.

[0169] The circuit board assembly 1 may further include a first electronic component 321 and a second electronic component 421. The first electronic component 321 is mounted on the first connection pad 32, and the second electronic component 421 is mounted on the second connection pad 42. Figure 22 When energized, the first coil 31 generates a magnetic field, which attracts the magnetic particles P on the first conductive layer 180 to move toward the first coil 31. Furthermore, the movement of the magnetic particles P on the first conductive layer 180 drives the flexible region 100b to move synchronously, causing this portion of the flexible region 100b to bend to form a curved portion 100b1 and be accommodated within the corresponding groove 24 in the first outer circuit board 300. When energized, the second coil 41 generates a magnetic field, which attracts the magnetic particles P on the second conductive layer 190 to move toward the second coil 41. Furthermore, the movement of the magnetic particles P on the second conductive layer 190 drives the flexible region 100b to move synchronously, causing this portion of the flexible region 100b to bend to form a curved portion 100b1 and be accommodated within the corresponding groove 24 in the second outer circuit board 400.

[0170] like Figure 24As shown, in other embodiments of the circuit board assembly 2, the flexible region 100b is a curved structure formed by heat setting, and the curved structure includes a plurality of curved portions 100b1 sequentially connected in the second direction Y, with adjacent curved portions 100b1 having opposite bending directions. Each curved portion 100b1 is received in a corresponding groove 24 of the first outer circuit board 300 or the second outer circuit board 400.

[0171] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present application should not depart from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing a retractable circuit board assembly, characterized in that: include: A flexible circuit board is provided, the flexible circuit board comprising a first base layer and an inner circuit layer stacked in a first direction, the flexible circuit board comprising a connection area and a retractable area arranged in a second direction perpendicular to the first direction, the inner circuit layer in the connection area comprising an electrical connection portion, and the retractable area is used to deform to form curved portions connected in sequence in the second direction; An outer circuit board is arranged on the inner circuit layer, and the electrical connection portion is exposed on the outer circuit board. The retractable area is used to make the electrical connection portion retract in the second direction compared with the outer circuit board during deformation and deformation recovery. The outer circuit board includes a second base layer and an outer circuit layer stacked in the first direction. The second base layer is located between the outer circuit layer and the inner circuit layer. A groove is provided on the surface of the second base layer away from the outer circuit layer, and the groove is used to accommodate the bent portion.

2. The method for preparing a retractable circuit board assembly according to claim 1, characterized in that: Before providing the outer circuit board, the preparation method further comprises: laminating a plurality of magnetic particles on the inner circuit layer in the retractable area; Setting the outer circuit board specifically includes: forming a coil in the outer circuit layer, the groove and the coil are correspondingly arranged in the first direction, and the coil is used to generate a magnetic field when powered on, thereby attracting the magnetic particles to move toward the direction of the coil, thereby driving the retractable area to bend to form the bent portion.

3. The method for preparing a retractable circuit board assembly according to claim 2, characterized in that: Before laminating the magnetic particles, the preparation method further comprises: laminating a conductive layer on the inner circuit layer in the retractable region, wherein the magnetic particles are laminating on the conductive layer.

4. The method for preparing a retractable circuit board assembly according to claim 3, characterized in that: Before providing the outer circuit board, the preparation method further includes: forming a through groove in the flexible circuit board, wherein at least a portion of the through groove is located at the bent portion; A connection column is formed on a surface of the second base layer away from the outer circuit layer, wherein after the outer circuit layer is arranged, the connection column can be slidably arranged in the through groove.

5. The method for preparing a retractable circuit board assembly according to claim 1, characterized in that: Before providing the outer circuit board, the preparation method further includes: Part of the flexible circuit board is formed into the bending parts connected in sequence in the second direction by heat setting, wherein after the outer circuit board is arranged, each bending part is correspondingly accommodated in one of the grooves.

6. A retractable circuit board assembly, characterized in that: include: A flexible circuit board, comprising a first base layer and an inner circuit layer stacked in a first direction, the flexible circuit board comprising a connection area and a retractable area arranged in a second direction perpendicular to the first direction, the inner circuit layer in the connection area comprising an electrical connection portion, and the retractable area being used to deform to form curved portions connected in sequence in the second direction; An outer circuit board is arranged on the inner circuit layer, the electrical connection portion is exposed on the outer circuit board, the retractable area is used to make the electrical connection portion retract in the second direction compared to the outer circuit board during deformation and deformation recovery, the outer circuit board includes a second base layer and an outer circuit layer stacked in the first direction, the second base layer is located between the outer circuit layer and the inner circuit layer, and a groove is provided on the surface of the second base layer away from the outer circuit layer, and the groove is used to accommodate the bent portion.

7. The retractable circuit board assembly according to claim 6, wherein: The retractable area includes a curved structure, and the curved structure includes curved portions connected in sequence in the second direction, and each curved portion is correspondingly received in the corresponding groove of the outer circuit board.

8. The retractable circuit board assembly according to claim 6 or 7, characterized in that: A through groove is also formed in the flexible circuit board, and the through groove is at least partially located in the bending portion; the outer circuit board also includes a connecting column arranged on the surface of the second base layer away from the outer circuit layer, and the connecting column can be slidably arranged in the through groove.

9. A retractable circuit board assembly, characterized in that: include: A flexible circuit board, comprising a first base layer and an inner circuit layer stacked in a first direction, the flexible circuit board comprising a connection area and a retractable area arranged in a second direction perpendicular to the first direction, the inner circuit layer in the connection area comprising an electrical connection portion, and the flexible circuit board further comprising a plurality of magnetic particles attached to the inner circuit layer in the retractable area; An outer circuit board is arranged on the inner circuit layer, the electrical connection portion is exposed from the outer circuit board, the outer circuit board includes a second base layer and an outer circuit layer stacked in the first direction, the second base layer is located between the outer circuit layer and the inner circuit layer, the outer circuit layer includes a coil, the coil is used to generate a magnetic field when energized, thereby attracting the magnetic particles to move toward the direction of the coil, thereby driving the retractable area to bend to form curved portions connected in sequence in the second direction.

10. The retractable circuit board assembly according to claim 9, wherein: A groove is provided on a surface of the second base layer away from the outer circuit layer, and the groove is used to accommodate the bent portion.

11. The retractable circuit board assembly according to claim 10, wherein: The flexible circuit board also includes a conductive layer, the conductive layer is attached to the inner circuit layer in the retractable area, and the magnetic particles are attached to the conductive layer.

12. The retractable circuit board assembly according to any one of claims 9 to 11, characterized in that: A through groove is also formed in the flexible circuit board, and the through groove is at least partially located in the bending portion; the outer circuit board also includes a connecting column arranged on the surface of the second base layer away from the outer circuit layer, and the connecting column can be slidably arranged in the through groove.

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