Telescoping circuit board assembly and method of making same

Abstract

A scalable circuit board assembly and a method for manufacturing the same. The method comprises: 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 scalable region arranged in a second direction, the inner circuit layer in the connection region comprising an electrical connection portion, the scalable region being configured to deform to form a bending portion connected in sequence in the second direction; disposing an outer circuit board on the inner circuit layer, and exposing the electrical connection portion from the outer circuit board, the scalable region being configured to stretch and contract the electrical connection portion in the second direction relative to the outer circuit board during deformation and 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 surface of the second base layer away from the outer circuit layer being provided with a groove, the groove being configured to accommodate the bending portion.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit board, and in particular to a scalable circuit board assembly and a preparation method thereof. BACKGROUND

[0002] Currently, people have higher and higher requirements for display technology. As a kind of revolutionary display technology, the scroll screen technology has gradually attracted people's attention.

[0003] Flexible circuit boards are widely used in electronic products due to their flexibility. The screen and the mainboard of the electronic product can be electrically connected through the flexible circuit board, so as to realize signal conduction, screen display control and other functions. However, the flexible circuit board is usually not scalable, so it is difficult to control the screen to stretch and shrink, thereby limiting the application of the flexible circuit board in the scroll screen field. SUMMARY

[0004] Therefore, it is necessary to provide a scalable circuit board assembly.

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

[0006] The first aspect of the present application provides a preparation method of a scalable circuit board assembly, comprising: providing a flexible circuit board, the flexible circuit board comprising a first base layer and an inner side circuit layer which are arranged in a first direction in a stacking manner, the flexible circuit board comprising a connection area and a scalable area which are arranged in a second direction perpendicular to the first direction, the inner side circuit layer in the connection area comprising an electrical connection part, the scalable area being used to deform to form a bending part which is connected in sequence in the second direction; arranging an outer side circuit board on the inner side circuit layer and exposing the electrical connection part from the outer side circuit board, the scalable area being used to stretch and shrink the electrical connection part in the second direction compared with the outer side circuit board when deforming and recovering, the outer side circuit board comprising a second base layer and an outer side circuit layer which are arranged in the first direction in a stacking manner, the second base layer being located between the outer side circuit layer and the inner side circuit layer, a surface of the second base layer away from the outer side circuit layer being provided with a groove, the groove being used to accommodate the bending part.

[0007] In some possible implementation manners, before the outer side circuit board is arranged, the preparation method further comprises: adhering a plurality of magnetic particles on the inner side circuit layer in the scalable area. Arranging the outer side circuit board specifically comprises: forming a coil in the outer side circuit layer, the groove and the coil being arranged correspondingly in the first direction, the coil being used to generate a magnetic field when energized, so as to attract the magnetic particles to move towards the direction of the coil, thereby driving the scalable area to bend to form the bending part.

[0008] In some possible implementations, the fabrication method further includes, prior to attaching the magnetic particles, attaching a conductive layer to the inner circuitry layer within the stretchable region, wherein the magnetic particles are attached to the conductive layer.

[0009] In some possible implementations, before setting the outer circuit board, the fabrication method further includes: forming a through groove in the flexible circuit board, the through groove being at least partially located in the bend; and forming a connecting post on the surface of the second base layer opposite to the outer circuit layer, wherein the connecting post is slidably disposed within the through groove after the outer circuit layer is set.

[0010] In some possible implementations, before setting the outer circuit board, the preparation method further includes: forming a portion of the flexible circuit board into the curved portions connected sequentially in the second direction by heat setting, wherein after setting the outer circuit board, each of the curved portions is correspondingly received in a groove.

[0011] A second aspect of this application provides a stretchable circuit board assembly, including a flexible circuit board and an outer circuit board disposed on an inner circuit layer. The flexible circuit board includes a first base layer and an inner circuit layer stacked in a first direction. The flexible circuit board includes a connection region and a stretchable region arranged in a second direction perpendicular to the first direction. The inner circuit layer within the connection region includes an electrical connection portion exposed on the outer circuit board. The stretchable region is configured to deform to form a bend sequentially connected in the second direction. The stretchable region is configured to allow the electrical connection portion to stretch relative to the outer circuit board in the second direction 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 facing away from the outer circuit layer for accommodating the bend.

[0012] In some possible implementations, the stretchable area includes a curved structure comprising curved portions connected sequentially in a second direction, each of the curved portions being received in a corresponding groove on the outer circuit board.

[0013] In some possible implementations, the flexible circuit board also has a through groove, which is at least partially located in the bend; the outer circuit board also includes a connecting post disposed on the surface of the second base layer opposite to the outer circuit layer, the connecting post being slidably disposed in the through groove.

[0014] The third aspect of the present application provides a scalable circuit board assembly, 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 connecting region and a scalable region arranged in a second direction perpendicular to the first direction, the inner circuit layer in the connecting region comprises an electrical connection part. The flexible circuit board further comprises a plurality of magnetic particles attached to the inner circuit layer in the scalable region. The outer circuit board is arranged on the inner circuit layer, and the electrical connection part is exposed to the outer circuit board. The outer circuit board comprises a second base layer and an outer circuit layer stacked in the first direction, and the second base layer is located between the outer circuit layer and the inner circuit layer. The outer circuit layer comprises a coil for generating a magnetic field when energized, thereby attracting the magnetic particles to move towards the direction of the coil, and further driving the scalable region to bend to form a bending part connected in sequence in the second direction.

[0015] In some possible implementation manners, a surface of the second base layer away from the outer circuit layer is provided with a groove for accommodating the bending part.

[0016] In some possible implementation manners, the flexible circuit board further comprises a conductive layer attached to the inner circuit layer in the scalable region, and the magnetic particles are attached to the conductive layer.

[0017] In some possible implementation manners, a through groove is further formed in the flexible circuit board, and the through groove is at least partially located in the bending part; and the outer circuit board further comprises a connecting column arranged on a surface of the second base layer away from the outer circuit layer, and the connecting column is slidably arranged in the through groove.

[0018] In the present application, since the scalable region can be deformed to form a bending part connected in sequence in the second direction, the electrical connection part is stretched or contracted in the second direction compared with the outer circuit board, so that the circuit board assembly achieves a scalable effect, and the circuit board assembly can be used to connect with a scroll screen and achieve the purpose of stretching or shortening the scroll screen. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A structure diagram of a first copper-clad substrate provided for an embodiment of the present application is shown.

[0020] Figure 2 A structure diagram of the first copper-clad substrate after forming a first conductive part is shown. Figure 1

[0021] Figure 3 A structure diagram of the first copper-clad substrate after etching the first conductive part is shown. Figure 2 ​Structure diagram of the first copper-clad substrate shown and after forming the inner side circuit layer.

[0022] Figure 4 To form a cover layer on the inner side circuit layer shown. Figure 3 Structure diagram of the flexible circuit board obtained after forming a protective layer on the inner side circuit layer shown.

[0023] Figure 5 To form a conductive cloth on the inner side circuit layer shown. Figure 4 Structure diagram of the flexible circuit board obtained after forming a protective layer on the inner side circuit layer shown.

[0024] Figure 6 To form a conductive cloth on the inner side circuit layer shown. Figure 5 Structure diagram of the flexible circuit board obtained after forming a protective layer on the inner side circuit layer shown.

[0025] Figure 7 To form a conductive cloth on the inner side circuit layer shown. Figure 6 Structure diagram of the flexible circuit board obtained after forming a protective layer on the inner side circuit layer shown.

[0026] Figure 8A To form a conductive cloth on the inner side circuit layer shown. Figure 7 Structure diagram of the flexible circuit board obtained after forming a protective layer on the inner side circuit layer shown.

[0027] Figure 8B Structure diagram of the flexible circuit board obtained after forming a protective layer on the inner side circuit layer shown. Figure 8A Structure diagram of the flexible circuit board obtained after forming a protective layer on the inner side circuit layer shown.

[0028] Figure 9 Structure diagram of the second copper-clad substrate provided by an embodiment of the present application.

[0029] Figure 10 To form a connecting column on the second copper-clad substrate shown. Figure 9 Structure diagram of the substrate unit obtained after forming a connecting column on the second copper-clad substrate shown.

[0030] Figure 11 To form a connecting column on the second copper-clad substrate shown. Figure 10 Structure diagram of the substrate unit obtained after forming a connecting column on the second copper-clad substrate shown.

[0031] Figure 12 To form a connecting column on the second copper-clad substrate shown. Figure 11 Structure diagram of the substrate unit obtained after forming a connecting column on the second copper-clad substrate shown.

[0032] Figure 13 To form a connecting column on the second copper-clad substrate shown. Figure 12 Structure diagram of the substrate unit obtained after forming a connecting column on the second copper-clad substrate shown.

[0033] Figure 14 To form a connecting column on the second copper-clad substrate shown. Figure 13 Structure diagram of the substrate unit obtained after forming a connecting column on the second copper-clad substrate shown.

[0034] Figure 15 To form a connecting column on the second copper-clad substrate shown. Figure 14Structure of the substrate unit after forming the second through-hole.

[0035] Figure 16 For etching Figure 15 Structure of the substrate unit after forming the metal layer of the outer circuit layer.

[0036] Figure 17 For forming the cover layer on the outer circuit layer Figure 16 Structure of the substrate unit after forming the cover layer on the outer circuit layer.

[0037] Figure 18 For forming the protective layer on the outer circuit layer Figure 17 Structure of the substrate unit after forming the protective layer on the outer circuit layer.

[0038] Figure 19 For removing Figure 18 Structure of the substrate unit after removing the part of the outer circuit layer.

[0039] Figure 20 For mounting the electronic component on the outer circuit layer Figure 19 Structure of the circuit board assembly after mounting the electronic component on the outer circuit layer.

[0040] Figure 21 For shrinking the circuit board assembly Figure 20 Structure of the circuit board assembly at B.

[0041] Figure 22 For shrinking the circuit board assembly Figure 20 Structure of the circuit board assembly after shrinking.

[0042] Figure 23 Structure of the flexible circuit board according to another embodiment of the present application.

[0043] Figure 24 Structure of the circuit board assembly prepared from the flexible circuit board. Figure 23

[0044] Main element symbol explanation

[0045] Circuit board assembly 1, 2

[0046] First copper clad substrate 10

[0047] First metal layer 11

[0048] Second metal layer 12

[0049] First base layer 13

[0050] First blind hole 14

[0051] First through-hole 15

[0052] ​First inner side circuit layer 16

[0053] Second inner side circuit layer 17

[0054] First cover layer 18

[0055] Second cover layer 19

[0056] Second copper clad substrate 20

[0057] Third metal layer 21

[0058] Second base layer 22

[0059] Connecting post 23

[0060] Groove 24

[0061] Connecting material 25

[0062] Connecting layer 25'

[0063] Second blind hole 26

[0064] Second conductive portion 27

[0065] Third cover layer 28

[0066] Fourth cover layer 29

[0067] First outer side circuit layer 30

[0068] First coil 31

[0069] First connecting pad 32

[0070] Second outer side circuit layer 40

[0071] Second coil 41

[0072] Second connecting pad 42

[0073] Flexible circuit board 100

[0074] Connecting region 100a

[0075] Stretchable region 100b

[0076] Bend 100b1

[0077] Through slot 101

[0078] Electrically connecting 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] third protective layer 420

[0088] second electronic component 421

[0089] substrate unit L

[0090] magnetic particle P

[0091] intermediate body I

[0092] first direction X

[0093] second direction Y

[0094] third direction Z

[0095] distance W1

[0096] width W2

[0097] The following detailed description will further describe the present application with reference to the above drawings. DETAILED DESCRIPTION

[0098] In order to more clearly understand the above objectives, features and advantages of the present application, the following will describe the present application in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict. In the following description, a lot of specific details are set forth in order to facilitate a full understanding of the present application. The described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work under the premise that there is no conflict, all belong to the scope of protection of the present application.

[0099] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes all and any combinations of one or more of the associated listed items.

[0100] In the embodiments of the present application, for the convenience of description but not limitation of the present application, the term "connection" used in the patent application specification and claims of the present application is not limited to physical or mechanical connection, whether direct or indirect. "Up", "down", "above", "below", "left", "right" and the like are only used to indicate relative positional relationship, which changes when the absolute position of the described object changes.

[0101] An embodiment of the present application provides a preparation method of a scalable circuit board assembly 1, comprising the following steps:

[0102] Step S1, please refer to Figure 1 provides a first copper-clad substrate 10, which comprises a first metal layer 11, a first base layer 13 and a second metal layer 12 which are sequentially stacked in a first direction X.

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

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

[0105] Step S2, please refer to Figure 2 forms a first blind hole 14 in the first copper-clad substrate 10, and electroplating metal in the first blind hole 14 to obtain at least one first conducting part 15. The first conducting part 15 is used to electrically connect the first metal layer 11 and the second metal layer 12.

[0106] In some embodiments, the first blind hole 14 penetrates the first metal layer 11 and the first base layer 13 in sequence, and the second metal layer 12 serves as the bottom of the first blind hole 14. The material of the first conducting part 15 can be copper.

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

[0108] Step S3, please refer to Figure 3etching the first metal layer 11 to obtain the first inner side circuit layer 16 and etching the second metal layer 12 to obtain the second inner side circuit layer 17. The first inner side circuit layer 16 is provided with an electrical connection part 160, which is used for connecting the flexible circuit board assembly 1 to external components (e.g. a screen or a main board of an electronic product, not shown in the figure) in the subsequent process.

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

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

[0111] Step S4, please refer to Figure 4 A first cover layer 18 is formed on the first inner side circuit layer 16 and a second cover layer 19 is formed on the second inner side circuit layer 17. The electrical connection part 160 is exposed from the first cover layer 18, i.e. the first cover layer 18 does not cover the electrical connection part 160.

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

[0113] Step S5, please refer to Figure 5 A surface treatment is performed on the electrical connection part 160 to form a first protective layer 161, and a flexible circuit board 100 is obtained. The flexible circuit board 100 comprises a connection area 100a and a stretchable area 100b arranged in a second direction Y perpendicular to a first direction X. The first inner side circuit layer 16 in the connection area 100a comprises the electrical connection part 160.

[0114] The first protective layer 161 is used to prevent the electrical connection part 160 from being oxidized on the surface in the subsequent process, thereby affecting the electrical performance of the electrical connection part 160. The surface treatment can be performed by using chemical gold plating, chemical nickel plating, etc. In other embodiments, the first protective layer 161 can also be an organic solderability preservative (OSP) protective layer.

[0115] It can be understood that the embodiments are described by taking an example that the flexible circuit board 100 comprises one first inner side circuit layer 16 and one second inner side circuit layer 17. In other embodiments, the number of circuit layers contained in the flexible circuit board 100 is not limited to two.

[0116] Step S6, please refer to Figure 6 A first conductive layer 180 is attached to the first cover layer 18 in the stretchable area 100b and a second conductive layer 190 is attached to the second cover layer 19 in the stretchable area 100b.

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

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

[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 (i.e., a magnetic ceramic).

[0120] Step S8, please refer to Figure 8A At least one through slot 101 is formed in the flexible circuit board 100, and the through slot 101 is at least partially disposed in the stretchable region 100b.

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

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

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

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

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

[0126] In some embodiments, the connecting column 23 can be formed by electroplating metal, and the material of the connecting column 23 can be copper. In some embodiments, the number of connecting columns 23 can be multiple.

[0127] Step S11, please refer to Figure 11At least one groove 24 is formed on the surface of the second substrate 22 away from the third metal layer 21. In the second direction Y, the groove 24 is arranged away from the connecting post 23, that is, the groove 24 is formed on the surface of the second substrate 22 in the region where the connecting post 23 is not arranged.

[0128] In some embodiments, the groove 24 can be formed by mechanical drilling or laser drilling, and in the cross section parallel to the first direction X and the second direction Y, the groove 24 can be semicircular or square. The number of grooves 24 can be multiple, and the multiple grooves 24 are arranged away from each other in the second direction Y. Further, the groove 24 can not pass through the entire second substrate 22 in the first direction X.

[0129] In step S12, referring to Figure 12 The connecting material 25 is arranged on the end of the connecting post 23 away from the second substrate 22 to obtain the substrate unit L.

[0130] In some embodiments, the connecting material 25 can be conductive paste, such as tin paste or copper paste.

[0131] In step S13, referring 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 post 23 and the groove 24 of each substrate unit L are arranged towards the flexible circuit board 100 to obtain the intermediate body I.

[0132] Before stacking, the connecting area 100a of the flexible circuit board 100 can be cut in advance to obtain the required shape. After stacking, the first conductive layer 180 and the second conductive layer 190 of the flexible circuit board 100 are respectively exposed to 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 connecting area 100a of the flexible circuit board 100 is also exposed to the corresponding adhesive layer 200, that is, the adhesive layer 200 does not cover the connecting area 100a.

[0133] At the same time, after stacking, the connecting post 23 of one substrate unit L passes through the through slot 101 of the flexible circuit board 100 and is aligned with the connecting post 23 of another substrate unit L. The grooves 24 of the two substrate units L are misaligned with 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 in the first conductive layer 180 or the second conductive layer 190.

[0134] When each substrate unit L includes a plurality of connecting posts 23, the distance W1 between the outer sides 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, so that the subsequent connecting posts 23 can slide in 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] At step S14, referring to Figure 13 , the intermediate body I is pressed so that the adhesive layer 200 connects each substrate unit L to the flexible circuit board 100.

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

[0137] At step S15, referring to Figure 14 , the connecting material 25 is cured to obtain a connecting layer 25', which fixes the connecting posts 23 of different substrate units L.

[0138] In some embodiments, the connecting material 25 (e.g., tin paste) can be cured by light curing.

[0139] At step S16, referring to 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 obtain at least one second conductive part 27. The second conductive part 27 is used to electrically connect the third metal layer 21 to the first inner side circuit layer 16 or the second inner side circuit layer 17.

[0140] In some embodiments, in the second direction Y, the stretchable area 100b is located between the connecting post 23 and the second conductive part 27. The stretchable area 100b protrudes from the adhesive layer 200 in the second direction Y, i.e., the stretchable area 100b is not covered by the adhesive layer 200. The second blind hole 26 penetrates the third metal layer 21, the second base layer 22 and the adhesive layer 200 in sequence, and the first inner side circuit layer 16 or the second inner side circuit layer 17 serves as the bottom of the second blind hole 26. The second conductive part 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] At step S17, referring to Figure 16, etching the third metal layer 21 of each substrate unit L to obtain a first outer circuit layer 30 and a second outer circuit layer 40 respectively. The first outer circuit layer 30 is located at the side of the first conductive layer 180 and includes at least one first coil 31. The second outer circuit layer 40 is located at the 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 includes a plurality of first coils 31, each of which is arranged in the first direction X corresponding to one of the grooves 24 of the corresponding substrate unit L. The second outer circuit layer 40 includes a plurality of second coils 41, each of which is arranged in the first direction X corresponding to one of the grooves 24 of the corresponding substrate unit L. The third metal layer 21 can 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 circuit layer 30, and a fourth cover layer 29 is formed on the second outer circuit layer 40. Part of the first outer circuit layer 30 is exposed from the third cover layer 28 to form a first connection pad 32, and part of the second outer circuit 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 can be a cover film (CVL) or a solder mask layer.

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

[0147] The second protective layer 320 is used to prevent the first connection pad 32 from being surface oxidized in the subsequent process, thereby affecting the electrical performance of the first connection pad 32. The third protective layer 420 is used to prevent the second connection pad 42 from being surface oxidized in the subsequent process, thereby affecting the electrical performance of the second connection pad 42. The surface treatment can be chemical gold plating, chemical nickel plating, etc. In other embodiments, the second protective layer 320 or the third protective layer 420 can also be an organic solderability preservative (OSP) protective layer.

[0148] It can be understood that the embodiment takes the first outer side circuit board 300 including one first outer side circuit layer 30 and the second outer side circuit board 400 including one second outer side circuit layer 40 as an example for illustration. In other embodiments, the number of circuit layers included in the first outer side circuit board 300 is not limited to one, and the number of circuit layers included in the second outer side circuit board 400 is not limited to one. For example, the first outer side circuit board 300 can also be provided with a circuit layer on the surface where the groove 24 is formed. For another example, after etching the third metal layer 21 to obtain a circuit layer, other circuit layers can be continuously formed on the circuit layer through a build-up process, and the circuit layer located at the outermost side is the first outer side circuit layer 30. The number of circuit layers included in the first outer side circuit board 300 and the second outer side circuit board 400 can be the same or different.

[0149] Step S20, please refer to Figure 19 , remove the first outer side circuit board 300 and the second outer side circuit board 400 located on both sides of the connecting area 100a of the flexible circuit board 100, so that the connecting area 100a is exposed. Moreover, the connecting area 100a of the flexible circuit board 100 extends out of the first outer side circuit board 300 and the second outer side circuit board 400 in the second direction Y.

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

[0151] Among them, Figure 21 The circuit board assembly 1 of Figure 20 is shown in the top view of part A. As shown in Figure 21 , two through grooves 101 can be formed on the flexible circuit board 100, and the two through grooves 101 are arranged apart in the third direction Z perpendicular to the first direction X and the second direction Y. Each through groove 101 is in the shape of a long strip extending along the second direction Y. Two connecting posts 23 are slidingly arranged in each through groove 101.

[0152] In operation, as Figure 22As shown, the first outer circuit layer 30 is powered on, so that the first coil 31 is powered on, and the first coil 31 generates a magnetic field after being powered on, thereby attracting the magnetic particles P on the first conductive layer 180 to move towards the direction close to the first coil 31, and the magnetic particles P on the first conductive layer 180 will drive the corresponding stretchable area 100b to move synchronously when moving, so that the part of the stretchable area 100b is bent to form a bending part 100b1 and is accommodated in the corresponding groove 24 in the first outer circuit board 300; similarly, the second outer circuit layer 40 is powered on, so that the second coil 41 is powered on, and the second coil 41 generates a magnetic field after being powered on, thereby attracting the magnetic particles P on the second conductive layer 190 to move towards the direction close to the second coil 41, and the magnetic particles P on the second conductive layer 190 will drive the corresponding stretchable area 100b to move synchronously when moving, so that the part of the stretchable area 100b is bent to form a bending part 100b1 and is accommodated in the corresponding groove 24 in the second outer circuit board 400. At this time, the stretchable area 100b is deformed and forms the bending parts 100b1 connected in sequence in the second direction Y, and the bending directions of the adjacent two bending parts 100b1 are opposite. Because different parts of the stretchable area 100b bend in opposite directions, it appears that the connection area 100a is retracted in the second direction Y, that is, the length of the connection area 100a extending out of the first outer circuit board 300 and the second outer circuit board 400 becomes shorter, or even zero.

[0153] As shown in FIG. 1, the first outer circuit layer 30 and the second outer circuit layer 40 are powered on, so that the first coil 31 and the second coil 41 are powered on, and the first coil 31 and the second coil 41 generate magnetic fields after being powered on, thereby attracting the magnetic particles P on the first conductive layer 180 and the second conductive layer 190 to move towards the direction close to the first coil 31 and the second coil 41, and the magnetic particles P on the first conductive layer 180 and the second conductive layer 190 will drive the corresponding stretchable area 100b to move synchronously when moving, so that the part of the stretchable area 100b is bent to form a bending part 100b1 and is accommodated in the corresponding groove 24 in the first outer circuit board 300 and the second outer circuit board 400. Figure 20 As shown in FIG. 1, the first outer circuit layer 30 and the second outer circuit layer 40 are powered on, so that the first coil 31 and the second coil 41 are powered on, and the first coil 31 and the second coil 41 generate magnetic fields after being powered on, thereby attracting the magnetic particles P on the first conductive layer 180 and the second conductive layer 190 to move towards the direction close to the first coil 31 and the second coil 41, and the magnetic particles P on the first conductive layer 180 and the second conductive layer 190 will drive the corresponding stretchable area 100b to move synchronously when moving, so that the part of the stretchable area 100b is bent to form a bending part 100b1 and is accommodated in the corresponding groove 24 in the first outer circuit board 300 and the second outer circuit board 400.

[0154] In the above stretching and retracting process, the connecting column 23 can slide back and forth in the through groove 101, thereby playing a guiding role in the second direction Y, so that the flexible circuit board 100 can stretch and retract along the second direction Y under the cooperation of the connecting column 23 and the through groove 101. In addition, the first conductive layer 180 and the second conductive layer 190 can respectively play a role of electromagnetic shielding, that is, shielding the interference signals generated by the first coil 31 and the second coil 41, to prevent the above interference signals from affecting the normal work of the first inner circuit layer 16 and the second inner circuit layer 17. In other embodiments, the connecting column 23 and the through groove 101 can also be omitted. The first conductive layer 180 and the second conductive layer 190 can also be omitted.

[0155] It can be understood that in some embodiments of the present application, the plurality of first coils 31 contained in the first outer circuit layer 30 can be independently controlled, that is, each first coil 31 can be independently powered. Similarly, the plurality of second coils 41 contained in the second outer circuit layer 40 can be independently controlled. By controlling the number of powered coils, the number of bending portions 100b 1 formed in the flexible circuit board 100 can be controlled. Therefore, the specific length of the flexible circuit board 100 during the stretching and contracting process can also be adjusted according to actual needs, thereby improving the degree of freedom of stretching and contracting.

[0156] Another embodiment of the present application also provides a preparation method of the circuit board assembly 2. Different from the preparation method of the above-mentioned embodiment, after obtaining the flexible circuit board 100 in step S5, the preparation method has the following steps:

[0157] Step S22, please refer to Figure 23 The stretchable area 100b is formed into a bending structure by heat setting.

[0158] After forming, the stretchable area 100b includes a plurality of bending portions 100b 1 connected in sequence in the second direction Y, and the bending directions of adjacent two bending portions 100b 1 are opposite.

[0159] Step S23, please refer to Figure 24 The substrate unit (not shown in the figure), the adhesive layer 200, the flexible circuit board 100, another adhesive layer 200 and another substrate unit are stacked in sequence, so that the plurality of bending portions 100b 1 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 in the figure), forming the third cover layer 28 and the fourth cover 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 element 321 and the second electronic element 421, etc. are sequentially performed, so as to obtain the circuit board assembly 2.

[0161] In this embodiment, when the connecting area 100a of the flexible circuit board 100 is pulled by an external force, the stretchable area 100b can be stretched under the action of the external force, so that the connecting area 100a is further stretched in the second direction Y, realizing the effect of stretching. When the external force is removed, the stretchable area 100b returns to the initial state, realizing the effect of contraction.

[0162] Please refer to Figure 20In an embodiment of the present application, a circuit board assembly 1 is provided, which is prepared by the above method. The circuit board assembly 1 comprises 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 which are sequentially stacked in a first direction X.

[0163] The flexible circuit board 100 comprises 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 the first direction X. The flexible circuit board 100 comprises a connecting region 100a and an expandable region 100b which are arranged in a second direction Y perpendicular to the first direction X. The first inner circuit layer 16 in the connecting region 100a comprises an electrical connecting portion 160 which is exposed to the outside of the circuit board. The expandable region 100b is used to deform to form a bending portion 100b1 which is sequentially connected in the second direction Y (see FIG. 2). Figure 22 The expandable region 100b is used to make the electrical connecting portion 160 expand and contract in the second direction Y compared with the first outer circuit board 300 and the second outer circuit board 400 when deforming and recovering.

[0164] The first outer circuit board 300 comprises a second base layer 22 and a first outer circuit layer 30 which are stacked in the first direction X. The second base layer 22 is located between the first outer circuit layer 30 and the first inner circuit layer 16. The surface of the second base layer 22 which faces away from the outer circuit layer can be provided with a plurality of grooves 24. The second outer circuit board 400 comprises another second base layer 22 and a second outer circuit layer 40 which are stacked in the first direction X. The second base layer 22 is located between the second outer circuit layer 40 and the second inner circuit layer 17. The surface of each second base layer 22 which faces away from the first outer circuit layer 30 or the second outer circuit layer 40 is provided with a plurality of grooves 24 which are used to accommodate the bending portion 100b1. In the present embodiment, the first outer circuit board 300 comprises one first outer circuit layer 30 and the second outer circuit board 400 comprises one 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, the surface of the first outer circuit board 300 which is provided with the grooves 24 can also be provided with circuit layers, i.e., the first outer circuit board 300 can be a double-sided circuit board. In other embodiments, the grooves 24 can be omitted.

[0165] In some embodiments, the flexible circuit board 100 further comprises 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 conductive layer 190 are both arranged corresponding to the expandable region 100b of the flexible circuit board 100. A plurality of magnetic particles P are attached to the first conductive layer 180 and the second conductive layer 190, respectively.

[0166] At least one through slot 101 is formed in the flexible circuit board 100, and the through slot 101 is at least partially located in the bendable portion 100b1. Each through slot 101 penetrates the first cover layer 18, the first inner side circuit layer 16, the first base layer 13, the second inner side circuit layer 17, and the second cover layer 19.

[0167] The first outer side circuit 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 connecting pad 32. The first connecting pad 32 is exposed to the third cover layer 28. Each first coil 31 is arranged in the first direction X corresponding to one of the recesses 24 of the first outer side circuit layer 300. The surface of the second base layer 22 facing away from the first outer side circuit layer 30 is further formed with at least one connecting column 23, and the recess 24 is formed in the area of the surface of the second base layer 22 where no connecting column 23 is arranged.

[0168] The second outer side circuit 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 connecting pad 42. The second connecting pad 42 is exposed to the fourth cover layer 29. Each second coil 41 is arranged in the first direction X corresponding to one of the recesses 24 of the second outer side circuit layer 400. The surface of the second base layer 22 facing away from the second outer side circuit layer 40 is formed with at least one connecting column 23 and at least one recess 24, and the recess 24 is formed in the area of the surface of the second base layer 22 where no connecting column 23 is arranged.

[0169] The circuit board assembly 1 can further include a first electronic component 321 and a second electronic component 421. The first electronic component 321 is mounted on the first connecting pad 32, and the second electronic component 421 is mounted on the second connecting pad 42. Please refer to Figure 22 When the first coil 31 is energized, a magnetic field is generated, thereby attracting the magnetic particles P on the first conductive layer 180 to move in the direction close to the first coil 31. When the magnetic particles P on the first conductive layer 180 move, the stretchable area 100b is synchronously moved, so that the part of the stretchable area 100b is bent to form the bendable portion 100b1 and is accommodated in the corresponding recess 24 of the first outer side circuit layer 300. When the second coil 41 is energized, a magnetic field is generated, thereby attracting the magnetic particles P on the second conductive layer 190 to move in the direction close to the second coil 41. When the magnetic particles P on the second conductive layer 190 move, the stretchable area 100b is synchronously moved, so that the part of the stretchable area 100b is bent to form the bendable portion 100b1 and is accommodated in the corresponding recess 24 of the second outer side circuit layer 400.

[0170] As shown in Figure 24As shown, in some other embodiments shown in the circuit board assembly 2, the stretchable area 100b is a bending structure formed by heat setting, and the bending structure includes a plurality of bending portions 100b1 connected in sequence in the second direction Y, and the bending directions of adjacent two bending portions 100b1 are opposite. Each bending portion 100b1 is accommodated in the corresponding groove 24 of the first outer side circuit board 300 or the second outer side circuit board 400.

[0171] The above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalent replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for manufacturing a scalable circuit board assembly, characterized in that, include: A flexible circuit board is provided, the flexible circuit board including a first base layer and an inner circuit layer stacked in a first direction, the flexible circuit board including a connection area and a stretchable area arranged in a second direction perpendicular to the first direction, the inner circuit layer in the connection area including an electrical connection portion, and the stretchable area being used to deform to form a curved portion sequentially connected in the second direction. An outer circuit board is disposed on the inner circuit layer, and the electrical connection portion is exposed on the outer circuit board. The stretchable area is used to allow the electrical connection portion to stretch or contract relative to the outer circuit board in the second direction 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. The surface of the second base layer facing away from the outer circuit layer is provided with a groove, which is used to accommodate the bent portion.

2. The method for manufacturing the stretchable circuit board assembly as described in claim 1, characterized in that, Before setting the outer circuit board, the fabrication method further includes: attaching a plurality of magnetic particles to the inner circuit layer within the stretchable region; The outer circuit board is specifically configured by forming a coil in the outer circuit layer, with the groove and the coil correspondingly arranged in the first direction. The coil is used to generate a magnetic field when energized, thereby attracting the magnetic particles to move toward the coil, which in turn causes the stretchable area to bend to form the curved portion.

3. The method for manufacturing the stretchable circuit board assembly as described in claim 2, characterized in that, Before attaching the magnetic particles, the preparation method further includes: attaching a conductive layer to the inner circuit layer within the stretchable region, wherein the magnetic particles are attached to the conductive layer.

4. The method for manufacturing the stretchable circuit board assembly as described in claim 3, characterized in that, Before setting the outer circuit board, the fabrication method further includes: A through-slot is formed in the flexible circuit board, and the through-slot is at least partially located in the bent portion; A connecting post is formed on the surface of the second base layer opposite to the outer circuit layer, wherein the connecting post is slidably disposed within the through groove after the outer circuit layer is disposed.

5. The method for manufacturing the stretchable circuit board assembly as described in claim 1, characterized in that, Before setting the outer circuit board, the fabrication method further includes: A portion of the flexible circuit board is formed into the curved portions that are sequentially connected in the second direction by heat setting, wherein after the outer circuit board is provided, each of the curved portions is correspondingly received in a groove.

6. A retractable circuit board assembly, characterized in that, include: A flexible circuit board includes a first base layer and an inner circuit layer stacked in a first direction. The flexible circuit board includes a connection area and a stretchable area arranged in a second direction perpendicular to the first direction. The inner circuit layer in the connection area includes an electrical connection portion. The stretchable area is used to deform to form a curved portion that is sequentially connected in the second direction. An outer circuit board is disposed on the inner circuit layer, and the electrical connection portion is exposed on the outer circuit board. The stretchable area is used to allow the electrical connection portion to stretch or contract relative to the outer circuit board in the second direction 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. The surface of the second base layer facing away from the outer circuit layer is provided with a groove, which is used to accommodate the bent portion.

7. The retractable circuit board assembly as claimed in claim 6, characterized in that, The retractable area includes a curved structure, which includes curved portions connected sequentially in a second direction, each of which is received in a corresponding groove on the outer circuit board.

8. The retractable circuit board assembly as claimed in claim 6 or 7, characterized in that, The flexible circuit board also has a through groove, which is at least partially located in the curved portion; the outer circuit board also includes a connecting post disposed on the surface of the second base layer opposite to the outer circuit layer, and the connecting post is slidably disposed in the through groove.

9. A retractable circuit board assembly, characterized in that, include: A flexible circuit board includes a first base layer and an inner circuit layer stacked in a first direction. The flexible circuit board includes a connection area and a stretchable area arranged in a second direction perpendicular to the first direction. The inner circuit layer in the connection area includes an electrical connection portion. The flexible circuit board also includes a plurality of magnetic particles attached to the inner circuit layer in the stretchable area. An outer circuit board is disposed on the inner circuit layer, and the electrical connection portion is exposed on 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 coil, thereby causing the stretchable area to bend to form a bend that is sequentially connected in the second direction. The second base layer has a groove on its surface away from the outer circuit layer, the groove being used to accommodate the bend.

10. The retractable circuit board assembly as claimed in claim 9, characterized in that, The flexible circuit board further includes a conductive layer, which is attached to the inner circuit layer within the stretchable area, and the magnetic particles are attached to the conductive layer.

11. The retractable circuit board assembly as claimed in claim 9 or 10, characterized in that, The flexible circuit board also has a through groove, which is at least partially located in the curved portion; the outer circuit board also includes a connecting post disposed on the surface of the second base layer opposite to the outer circuit layer, and the connecting post is slidably disposed in the through groove.

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