Soft-hard combined circuit board and preparation method thereof

Abstract

The application provides a preparation method of a rigid-flexible circuit board, comprising the following steps: providing an intermediate body comprising a circuit unit, a dielectric layer and a reinforcing member, wherein the circuit unit comprises a substrate, the substrate is divided into a first region, a second region and a third region, and comprises a first conductive circuit layer, a base material layer and a second conductive circuit layer, the second conductive circuit layer comprises a first circuit area arranged in the first region, the dielectric layer covers the first circuit area, and the reinforcing member is fixed on the base material layer in the second region; folding the second region around the reinforcing member, the dielectric layer is connected between the third region and the first region, and the substrate, the dielectric layer and the reinforcing member jointly form a cavity; and hot-pressing the folded substrate, so that the substrates located on both sides of the cavity are filled in the cavity and connected with each other to form two recesses arranged oppositely. The preparation method provided by the application is beneficial to simplifying the preparation process. The application further provides a rigid-flexible circuit board.

Description

Technical Field

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

[0002] The preparation of a rigid-flexible circuit board typically involves stacking a single-sided copper-clad substrate multiple times on a flexible circuit board, forming a build-up circuit unit from the copper layer of the single-sided copper-clad substrate, and then slotting to remove some of the build-up circuit unit, exposing a portion of the flexible circuit board to form a flex zone. However, the entire preparation process is relatively cumbersome. Furthermore, when reinforcing members are required in a rigid-flexible circuit board, they are often attached to the outer surface of the circuit board, making them susceptible to damage. Summary of the Invention

[0003] In view of this, the present application provides a method for preparing a rigid-flexible circuit board that is conducive to simplifying the preparation process.

[0004] The present application also provides a rigid-flexible circuit board.

[0005] The present application provides a method for preparing a rigid-flexible circuit board, comprising the following steps:

[0006] An intermediate is provided, comprising a circuit unit, a dielectric layer, and a reinforcement. The circuit unit comprises a substrate, wherein an extension direction of the substrate is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction. The substrate is divided into a first region, a second region, and a third region connected in sequence in the first direction. The substrate comprises a first conductive circuit layer, a base material layer, and a second conductive circuit layer stacked in sequence in the second direction. The second conductive circuit layer comprises a first circuit region provided in the first region. The dielectric layer covers the first circuit region. The reinforcement is fixed to the base material layer in the second region. The reinforcement is spaced apart from both the first region and the third region in the first direction. The second region is folded around the reinforcement so that the dielectric layer is connected between the third region and the first region. The folded substrate, the dielectric layer, and the reinforcement together form a cavity. The folded substrate is hot-pressed so that the substrates on both sides of the cavity are filled in the cavity and connected to each other to form two oppositely disposed grooves. The groove is located between the reinforcement and the dielectric layer, thereby obtaining the rigid-flexible circuit board.

[0007] In some possible embodiments, the second conductive circuit layer also includes a second circuit area provided in the third region, and the preparation of the circuit unit includes: forming a first hole in the first region that passes through the first circuit area and the substrate layer, and forming a second hole in the third region that passes through the substrate layer and the second circuit area; forming a first conductive paste portion in the first hole that electrically connects the first circuit area and the first conductive circuit layer, the first conductive paste portion is protruded from the first conductive circuit layer in the first circuit area, and forming a second conductive paste portion in the second hole that electrically connects the second circuit area and the first conductive circuit layer, the second conductive paste portion is protruded from the first conductive circuit layer in the second circuit area; attaching a dielectric layer with an opening to the first circuit area, and an end of the first conductive paste portion is provided in the opening; wherein, in the step of folding the second region, the end of the second conductive paste portion penetrates the opening and is connected to the first conductive paste portion, and the dielectric layer is connected between the first circuit area and the second circuit area.

[0008] In some possible embodiments, the preparation of the circuit unit also includes: forming a third hole and a fourth hole spaced apart in the second area, the third hole and the fourth hole both passing through the substrate layer, the third hole being located between the first circuit area and the fourth hole; forming a third conductive paste portion in the third hole, and forming a fourth conductive paste portion in the fourth hole, the third conductive paste portion and the fourth conductive paste portion both being electrically connected to the first conductive circuit layer; the preparation of the intermediate includes: fixing the reinforcement to the third conductive paste portion, the reinforcement being a conductive portion; in the step of folding the second area, the fourth conductive paste portion is connected to a surface of the reinforcement facing away from the third conductive paste portion.

[0009] In some possible embodiments, the preparation of the circuit unit also includes: forming a covering layer covering the first conductive circuit layer on the substrate; forming a release film layer covering at least the first circuit area and the second circuit area on the second conductive circuit layer, and the release film layer is located in the first area and the third area; forming a first through hole passing through the release film layer, the first circuit area and the substrate layer in the first area, and forming a second through hole passing through the release film layer, the second circuit area and the substrate layer in the third area; forming the first conductive paste portion in the first through hole, and forming the second conductive paste portion in the second through hole; removing the release film layer so that the first through hole forms the first hole and the second through hole forms the second hole; wherein, in the step of hot-pressing and folding the substrate, the covering layers located on both sides of the cavity move toward the cavity to be fixed in the groove.

[0010] In some possible embodiments, in the step of folding the second area, the side wall of the opening is spaced apart from the second conductive paste portion; in the step of pressing the folded substrate, the first conductive paste portion and the second conductive paste portion are both filled in the opening.

[0011] The present application also provides a rigid-flexible circuit board, the rigid-flexible circuit board comprising a circuit unit, a reinforcement member, and a dielectric layer;

[0012] The circuit unit includes a substrate, wherein an extension direction of the substrate is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction. The substrate is divided into a first region, a second region, and a third region connected in sequence in the first direction. The substrate includes a first conductive circuit layer, a base material layer, and a second conductive circuit layer stacked in sequence in the second direction. The second conductive circuit layer includes a first circuit area provided in the first region. The reinforcement is fixed to the base material layer in the second region. The reinforcement is spaced apart from the first region and the third region in the first direction. The second region of the substrate is folded around the reinforcement, and the third region is stacked on one side of the first region. The dielectric layer is connected between the first region and the third region and covers the first circuit area. Two portions of the substrate located between the reinforcement and the dielectric layer are bent toward the second conductive circuit layer and connected to each other to form two grooves facing away from each other. The grooves are located between the dielectric layer and the reinforcement.

[0013] In some possible embodiments, the second conductive circuit layer also includes a second circuit area provided in the third region, the dielectric layer is connected between the first circuit area and the second circuit area, the substrate is provided with a first hole passing through the first circuit area and the base material layer, and a second hole passing through the base material layer and the second circuit area; the circuit unit also includes a first conductive paste portion fixed to the first hole and electrically connecting the first circuit area and the first conductive circuit layer, and a second conductive paste portion fixed to the second hole and electrically connecting the second circuit area and the first conductive circuit layer, the first conductive paste portion is protruded away from the first conductive circuit layer in the first circuit area, and the second conductive paste portion is protruded away from the first conductive circuit layer in the second circuit area; the dielectric layer is provided with an opening, and the first conductive paste portion and the second conductive paste portion are also filled in the opening and are electrically connected.

[0014] In some possible embodiments, a third hole and a fourth hole are provided at intervals in the second area, and both the third hole and the fourth hole pass through the substrate layer. The circuit unit further includes a third conductive paste portion fixed to the third hole and a fourth conductive paste portion fixed to the fourth hole, and the third conductive paste portion is located between the first circuit area and the fourth conductive paste portion; the reinforcement is a conductive member, and the reinforcement is electrically connected between the third conductive paste portion and the fourth conductive paste portion.

[0015] In some possible implementations, the rigid-flex circuit board further includes a covering layer, and the covering layer covers the first conductive circuit layer.

[0016] In some possible implementations, the cover layer is provided with a window, and the window exposes a portion of the first conductive circuit layer outside the groove.

[0017] In the present application, after the substrate is folded around the reinforcement, the folded substrate is connected through a dielectric layer, and hot pressing is used to form a hard-flexible circuit board. The portion of the substrate located between the two grooves forms the flexing area of ​​the hard-flexible circuit board. The dielectric layer is connected to the first area and the third area to form the first rigid area of ​​the hard-flexible circuit board. The substrate covers the reinforcement to form the second rigid area of ​​the hard-flexible circuit board. The present application does not require multiple layer-adding operations and slotting operations. Therefore, the preparation method provided by the present application is conducive to simplifying the process. In addition, in the present application, the substrate covers the reinforcement after being folded around the reinforcement, so the substrate can protect the reinforcement, thereby solving the problem of easy damage to the reinforcement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A cross-sectional view of a cover layer provided in an embodiment of the present application covering a substrate;

[0019] Figure 2 For Figure 1 A cross-sectional view showing a substrate on which a release film layer is formed and a first through hole, a second through hole, a third hole, and a fourth hole are formed;

[0020] Figure 3 For Figure 2 A cross-sectional view showing the formation of the first conductive paste portion, the second conductive paste portion, the third conductive paste portion, and the fourth conductive paste portion in the first through hole, the second through hole, the third hole, and the fourth hole, and the removal of the release film layer;

[0021] Figure 4 For Figure 3 A cross-sectional view of the third conductive paste portion forming a reinforcing member is shown;

[0022] Figure 5 For Figure 4 A dielectric layer is formed on the substrate shown to obtain a cross-sectional view of the intermediate body;

[0023] Figure 6 For folding Figure 5 a cross-sectional view of the intermediate shown;

[0024] Figure 7 Hot pressing Figure 6 The cross-sectional view of the rigid-flex circuit board obtained after the intermediate is shown.

[0025] Description of main component symbols

[0026] Rigid-flexible circuit board 100 Circuit unit 10

[0027] Substrate 11 First conductive circuit layer 111

[0028] Base material layer 112 Second conductive circuit layer 113

[0029] First line area 1131 Second line area 1132

[0030] First hole 114 Second hole 115

[0031] Third hole 116 Fourth hole 117

[0032] First conductive paste portion 12 Second conductive paste portion 13

[0033] The third conductive paste portion 14 and the fourth conductive paste portion 15

[0034] Dielectric layer 20 opening 201

[0035] Reinforcement 30 Covering layer 40

[0036] Adhesive layer 41 Protective layer 42

[0037] Window 401 Groove 110

[0038] Cavity 105 Intermediate body 101

[0039] First area 102 Second area 103

[0040] The third region 104 release film layer 50

[0041] First through hole 51 Second through hole 52

[0042] First direction X Second direction Y

[0043] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0045] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. When an element is referred to as being "disposed on" another element, it may be directly disposed on the other element or there may be an intermediate element.

[0046] Example 1:

[0047] This application provides a method for preparing a rigid-flexible circuit board. Depending on different requirements, the order of the steps in the preparation method can be changed, and some steps can be omitted or combined. The preparation method includes the following steps:

[0048] Step 1: Reference Figure 1 , providing a substrate 11. The extension direction of the substrate is defined as a first direction X, and the direction perpendicular to the first direction is defined as a second direction Y. The substrate 11 can be divided into a first area 102, a second area 103 and a third area 104 connected in sequence in the first direction X. The substrate 11 includes a first conductive circuit layer 111, a base material layer 112 and a second conductive circuit layer 113 stacked in sequence in the second direction Y. Exemplarily, the material of the base material layer 112 can be a liquid crystal polymer. Exemplarily, the materials of the first conductive circuit layer 111 and the second conductive circuit layer 113 can both be copper. The second conductive circuit layer 113 includes a first circuit area 1131 provided in the first area 102 and a second circuit area 1132 provided in the third area 104. In another embodiment, the second conductive circuit layer 113 may not be provided with the second circuit area 1132.

[0049] Then, a cover layer 40 is formed on the substrate to cover the first conductive circuit layer 111. Exemplarily, the cover layer 40 includes a stacked adhesive layer 41 and a protective layer 42. The adhesive layer 41 is connected between the protective layer 42 and the first conductive circuit layer 111. Exemplarily, the adhesive layer 41 may be epoxy adhesive. The protective layer 42 may be made of polyimide or polyethylene terephthalate.

[0050] In some embodiments, the cover layer 40 is provided with a window 401 . The window 401 exposes a portion of the first conductive circuit layer 111 , so as to facilitate subsequent soldering of components, such as chips, connected to the first conductive circuit layer 111 at the window 401 .

[0051] Step 2: Reference Figure 2 A release film layer 50 is formed on the second conductive circuit layer 113 to cover the first circuit area 1131 and the second circuit area 1132. The release film layer 50 is located in the first area 102 and the third area 104. For example, the release film layer 50 can be a polyethylene terephthalate release film.

[0052] Then, a first through hole 51 is formed in the first region 102, penetrating the release film layer 50, the first circuit area 1131, and the substrate layer 112. A second through hole 52 is formed in the third region 104, penetrating the release film layer 50, the second circuit area 1132, and the substrate layer 112.

[0053] When the second conductive circuit layer 113 does not include the second circuit area 1132 , the release film layer 50 covering the third area 104 may cover the substrate layer 112 . The second through hole 52 may penetrate the release film layer 50 and the substrate layer 112 .

[0054] In some embodiments, a third hole 116 and a fourth hole 117 may be formed spaced apart in the second region 103. The third hole 116 and the fourth hole 117 both penetrate the substrate layer 112. The third hole 116 is located between the first circuit region 1131 and the fourth hole 117. For example, the first through hole 51, the second through hole 52, the third hole 116, and the fourth hole 117 may be formed by laser drilling.

[0055] Step 3: Reference Figure 2 and Figure 3 A first conductive paste portion 12 is formed in the first through hole 51. The first conductive paste portion 12 electrically connects the first circuit area 1131 and the first conductive circuit layer 111. The first conductive paste portion 12 is protruded from the first circuit area 1131 away from the first conductive circuit layer 111.

[0056] Furthermore, a second conductive paste portion 13 is formed in the second through hole 52. The second conductive paste portion 13 electrically connects the second circuit area 1132 and the first conductive circuit layer 111. The second conductive paste portion 13 is protruded from the second circuit area 1132 away from the first conductive circuit layer 111.

[0057] The first conductive paste portion 12 and the second conductive paste portion 13 are used to electrically connect the first conductive circuit layer 111 to the second conductive circuit layer 113. In another embodiment, the electrical connection between the first conductive circuit layer 111 and the second conductive circuit layer 113 can also be achieved by electroplating a conductive material on the inner wall of the through hole.

[0058] Furthermore, a third conductive paste portion 14 is formed in the third hole 116, and a fourth conductive paste portion 15 is formed in the fourth hole 117. Both the third conductive paste portion 14 and the fourth conductive paste portion 15 are electrically connected to the first conductive circuit layer 111. In some embodiments, at least one of the third conductive paste portion 14 and the fourth conductive paste portion 15 may protrude from the substrate layer 112 away from the first conductive circuit layer 111. The third conductive paste portion 14 is located between the fourth conductive paste portion 15 and the first circuit area 1131.

[0059] For example, tin paste or copper paste may be printed to form the first conductive paste portion 12 , the second conductive paste portion 13 , the third conductive paste portion 14 , and the fourth conductive paste portion 15 , respectively.

[0060] Then, the release film layer 50 is removed, leaving the first through-hole 51 as the first hole 114 and the second through-hole 52 as the second hole 115, thereby obtaining the circuit unit 10. The first hole 114 is located in the first region 102 and passes through the first circuit area 1131 and the substrate layer 112. The first conductive paste portion 12 is fixed to the first hole 114. The second hole 115 is located in the third region 104 and passes through the substrate layer 112 and the second circuit area 1132. The second conductive paste portion 13 is fixed to the second hole 115. The circuit unit 10 includes the substrate 11, the first conductive paste portion 12, the second conductive paste portion 13, the third conductive paste portion 14, and the fourth conductive paste portion 15.

[0061] In another embodiment, the first hole 114 penetrating the first circuit area 1131 and the substrate layer 112 may be formed directly in the first region 102 , and the second hole 115 penetrating the substrate layer 112 and the second circuit area 1132 may be formed directly in the third region 104 .

[0062] In another embodiment, the circuit unit 10 may be directly provided. The circuit unit 10 includes the substrate 11. The second conductive circuit layer 113 is electrically connected to the first conductive circuit layer 111. The circuit unit 10 may not include the first conductive paste portion 12, the second conductive paste portion 13, the third conductive paste portion 14, and the fourth conductive paste portion 15.

[0063] Step 4: Reference Figure 4 , fix the reinforcing piece 30 to the third conductive paste portion 14 so that the reinforcing piece 30 is fixed to the base material layer 112 in the second region 103 away from the first conductive circuit layer 111. The reinforcing piece 30 can be a conductive piece or an insulating piece. In this embodiment, the reinforcing piece 30 is a conductive piece. Exemplarily, the reinforcing piece 30 can be a steel reinforcing piece. The reinforcing piece 30 is spaced apart from both the first region 102 and the third region 104 in the first direction X. In this embodiment, the reinforcing piece 30 is spaced apart from both the first circuit area 1131 and the second circuit area 1132.

[0064] In another embodiment, the reinforcing member 30 may be fixed to the base material layer 112 in the second region 103 away from the first conductive circuit layer 111 by gluing.

[0065] Step 5: Reference Figure 5 A dielectric layer 20 having an opening 201 is attached to the first circuit area 1131 to form an intermediate body 101. The end of the first conductive paste portion 12 is disposed within the opening 201. The dielectric layer 20 is disposed in the first region 102 and covers the first circuit area 1131. Exemplarily, the dielectric layer 20 may be made of polypropylene. The intermediate body 101 includes the circuit unit 10, the dielectric layer 20, the reinforcing member 30, and the covering layer 40.

[0066] In another embodiment, the order of step four and step five can be swapped.

[0067] In some embodiments, the sidewall of the opening 201 is spaced apart from the first conductive paste portion 12 .

[0068] In another embodiment, the dielectric layer 20 may be formed in the first region 102 , and a portion of the dielectric layer 20 may be removed to form the opening 201 . In another embodiment, the first conductive paste portion 12 may be fixed to the opening 201 .

[0069] In another embodiment, when the circuit unit 10 is not provided with the first conductive paste portion 12 and the second conductive paste portion 13, or the first conductive paste portion 12 is not protruding from the first circuit area 1131 and the second conductive paste portion 13 is not protruding from the second circuit area 1132, the dielectric layer 20 may not be provided with the opening 201.

[0070] In another embodiment, the intermediate body 101 may be directly provided. The intermediate body 101 may not include the covering layer 40 .

[0071] Step 6: Reference Figure 5and Figure 6 The second region 103 is folded around the reinforcing member 30, so that the dielectric layer 20 is connected between the third region 104 and the first region 102. The folded substrate 11, the dielectric layer 20, and the reinforcing member 30 together form a cavity 105. In some embodiments, the end of the second conductive paste portion 13 penetrates the opening 201 and connects to the first conductive paste portion 12. In some embodiments, the sidewall of the opening 201 is spaced apart from the second conductive paste portion 13. In other embodiments, the second conductive paste portion 13 can be fixed to the opening 201.

[0072] In this embodiment, the dielectric layer 20 is connected between the first circuit area 1131 and the second circuit area 1132. When the second conductive circuit layer 113 does not include the second circuit area 1132, the dielectric layer 20 may be connected between the first circuit area 1131 and the substrate layer 112.

[0073] The fourth conductive paste portion 15 is connected to a surface of the reinforcing member 30 facing away from the third conductive paste portion 14. The reinforcing member 30 is connected to the first conductive circuit layer 111 through the third conductive paste portion 14 and the fourth conductive paste portion 15, thereby reducing the coupling capacitance of the first conductive circuit layer 111. The reinforcing member 30 can also be connected to a ground circuit.

[0074] Step 7: Reference Figure 6 and Figure 7 , the folded substrate 11 is hot-pressed to obtain a rigid-flexible circuit board 100. During the hot-pressing process, the substrates 11 on both sides of the cavity 105 are filled in the cavity 105 and connected to each other to form two oppositely disposed grooves 110. This allows the base material layer 112 located on the bottom wall of the cavity 105 to adhere to the base material layer 112 located on the top wall of the cavity 105. Correspondingly, the cover layer 40 also moves toward the cavity 105 along with the substrate 11 to be fixed in the groove 110. The groove 110 is located between the reinforcement 30 and the dielectric layer 20. The first conductive paste portion 12 and the second conductive paste portion 13 are both filled in the opening 201. The portion of the substrate 11 located between the two grooves 110 forms the flexure zone of the rigid-flexible circuit board 100. The dielectric layer 20 is connected to the first area 102 and the third area 104 to form the first rigid area of ​​the rigid-flexible circuit board 100. The substrate 11 covers the reinforcing member 30 to form a second rigid region of the rigid-flexible circuit board 100 .

[0075] In step 6, refer to Figure 6Before the substrate 11 is pressed together, the first conductive paste portion 12 and the second conductive paste portion 13 are both spaced apart from the sidewalls of the opening 201 , which can prevent the conductive paste from overflowing from the opening 201 when the substrate 11 is pressed together.

[0076] In the present application, after the substrate 11 is folded around the reinforcement 30, the substrate 11 is connected to the folding axis through the dielectric layer 20, and hot pressing is performed to form the rigid-flexible circuit board 100. The portion of the substrate 11 located between the two grooves 110 forms the flexing area of ​​the rigid-flexible circuit board 100. The dielectric layer 20 is connected to the first area 102 and the third area 104 to form the first rigid area of ​​the rigid-flexible circuit board 100. The substrate 11 covers the reinforcement 30 to form the second rigid area of ​​the rigid-flexible circuit board 100. The present application does not require multiple layering operations and slotting operations. Therefore, the preparation method provided in the present application is conducive to simplifying the process. In addition, in the present application, the substrate 11 is folded around the reinforcement 30 and then covered with the reinforcement 30, so the substrate 11 can protect the reinforcement 30, thereby solving the problem that the reinforcement 30 is easily damaged.

[0077] Example 2:

[0078] Reference Figure 7The present application also provides a rigid-flexible circuit board 100. The rigid-flexible circuit board includes a circuit unit 10, a reinforcement member 30, and a dielectric layer 20. The circuit unit 10 includes a substrate 11. The extension direction of the substrate is defined as a first direction X, and the direction perpendicular to the first direction is defined as a second direction Y. The substrate 11 is divided into a first region 102, a second region 103, and a third region 104, which are connected in sequence in the first direction X. The substrate 11 includes a first conductive circuit layer 111, a base material layer 112, and a second conductive circuit layer 113, which are stacked in sequence in the second direction Y. The second conductive circuit layer 113 includes a first circuit area 1131 provided in the first region 102. The reinforcement member 30 is fixed to the base material layer 112 in the second region 103, away from the first conductive circuit layer 111. The reinforcement member 30 is spaced apart from both the first region 102 and the third region 104 in the first direction X. The second region 103 of the substrate 11 is folded around the reinforcement member 30. The third region 104 is stacked on one side of the first region 102. The dielectric layer 20 is connected between the first region 102 and the third region 104 and covers the first circuit area 1131. The two portions of the substrate 11 located between the reinforcing member 30 and the dielectric layer 20 are bent toward the second conductive circuit layer 113 and connected to each other to form two grooves 110 facing away from each other. This allows the base material layer 112 located in one groove 110 to adhere to the base material layer 112 located in the other groove 110. The grooves 110 are located between the dielectric layer 20 and the reinforcing member 30.

[0079] In some embodiments, the second conductive circuit layer 113 further includes a second circuit region 1132 located in the third region 104. The dielectric layer 20 is connected between the first circuit region 1131 and the second circuit region 1132. The substrate 11 is provided with a first hole 114 extending through the first circuit region 1131 and the base layer 112, and a second hole 115 extending through the base layer 112 and the second circuit region 1132. The circuit unit 10 further includes a first conductive paste portion 12 secured to the first hole 114 and a second conductive paste portion 13 secured to the second hole 115. The first conductive paste portion 12 electrically connects the first circuit region 1131 and the first conductive circuit layer 111 and is disposed protruding from the first circuit region 1131 away from the first conductive circuit layer 111. The second conductive paste portion 13 electrically connects the second circuit region 1132 and the first conductive circuit layer 111 and is disposed protruding from the second circuit region 1132 away from the first conductive circuit layer 111.

[0080] The dielectric layer 20 is provided with an opening 201. The first conductive paste portion 12 and the second conductive paste portion 13 are both filled within the opening 201 and are electrically connected. The provision of the first conductive paste portion 12 and the second conductive paste portion 13 not only enables electrical continuity between the first circuit area 1131, the second circuit area 1132, and the first conductive circuit layer 111, but also improves the connection strength between the first region 102 and the third region 104. Furthermore, the dielectric layer 20 is connected between the first circuit area 1131 and the second circuit area 1132, further increasing the stacking thickness of the first region 102, the third region 104, and the dielectric layer 20, thereby further improving the rigidity of this stacking portion.

[0081] In another embodiment, the dielectric layer 20 may not be provided with the opening 201. The first conductive paste portion 12 may not be protruding from the first circuit area 1131. The second conductive paste portion 13 may not be protruding from the second circuit area 1132.

[0082] In some embodiments, a third hole 116 and a fourth hole 117 are spaced apart within the second region 103. The third hole 116 and the fourth hole 117 both penetrate the substrate layer 112. The circuit unit 10 further includes a third conductive paste portion 14 fixed to the third hole 116 and a fourth conductive paste portion 15 fixed to the fourth hole 117. The third conductive paste portion 14 is located between the first circuit area 1131 and the fourth conductive paste portion 15. The reinforcing member 30 is a conductive member electrically connected between the third conductive paste portion 14 and the fourth conductive paste portion 15. The provision of the reinforcing member 30, the third conductive paste portion 14, and the fourth conductive paste portion 15 helps reduce the coupling capacitance of the first conductive circuit layer 111.

[0083] In another embodiment, the reinforcing member 30 may be fixed by an adhesive layer. The reinforcing member 30 may be an insulating member.

[0084] In some embodiments, the rigid-flex circuit board 100 further includes a cover layer 40. The cover layer 40 covers the first conductive circuit layer 111. Exemplarily, the cover layer 40 includes a stacked adhesive layer 41 and a protective layer 42. The adhesive layer 41 is connected between the protective layer 42 and the substrate 11. The cover layer 40 is used to insulate and protect the substrate 11.

[0085] In some embodiments, the cover layer 40 has a window 401 that exposes a portion of the first conductive circuit layer 111 outside the groove 110 , so as to facilitate soldering of components, such as chips, connected to the first conductive circuit layer 111 at the window 401 .

[0086] Since the materials of the corresponding elements in this embodiment are the same as those of the corresponding elements in Embodiment 1, they will not be described in detail.

[0087] The above description is only an optimized specific implementation of the present application, but it is not limited to this implementation in actual application. For ordinary technicians in this field, other variations and changes made according to the technical concept of the present application should fall within the scope of protection of the present application.

Claims

1. A method for preparing a rigid-flexible circuit board, characterized in that: The steps include: An intermediate body is provided, comprising a circuit unit, a dielectric layer, and a reinforcing member. The circuit unit comprises a substrate, wherein an extension direction of the substrate is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction. The substrate is divided into a first region, a second region, and a third region connected in sequence in the first direction. The substrate comprises a first conductive circuit layer, a base material layer, and a second conductive circuit layer stacked in sequence in the second direction. The second conductive circuit layer comprises a first circuit region provided in the first region. The dielectric layer covers the first circuit region. The reinforcing member is fixed to the base material layer in the second region. The reinforcing member is spaced apart from both the first region and the third region in the first direction. Folding the second region around the reinforcing member so that the dielectric layer is connected between the third region and the first region, and the folded substrate, the dielectric layer and the reinforcing member together form a cavity; The substrate is folded by hot pressing so that the substrates on both sides of the cavity are filled in the cavity and connected to each other to form two grooves arranged opposite to each other. The grooves are located between the reinforcement and the dielectric layer, thereby obtaining the soft-rigid combination circuit board.

2. The method for preparing a rigid-flexible circuit board according to claim 1, wherein: The second conductive circuit layer further includes a second circuit area provided in the third region, and the preparation of the circuit unit includes: forming a first hole penetrating the first circuit area and the substrate layer in the first region, and forming a second hole penetrating the substrate layer and the second circuit area in the third region; A first conductive paste portion is formed in the first hole to electrically connect the first circuit area and the first conductive circuit layer, the first conductive paste portion being away from the first conductive circuit layer and protruding from the first circuit area; a second conductive paste portion is formed in the second hole to electrically connect the second circuit area and the first conductive circuit layer, the second conductive paste portion being away from the first conductive circuit layer and protruding from the second circuit area; Attaching a dielectric layer having an opening on the first circuit area, with an end portion of the first conductive paste portion being disposed in the opening; In the step of folding the second area, an end portion of the second conductive paste portion penetrates the opening and is connected to the first conductive paste portion, and the dielectric layer is connected between the first circuit area and the second circuit area.

3. The method for preparing a rigid-flexible circuit board according to claim 1 or 2, wherein: The preparation of the circuit unit further includes: forming a third hole and a fourth hole spaced apart in the second region, wherein both the third hole and the fourth hole penetrate the substrate layer, and the third hole is located between the first circuit region and the fourth hole; forming a third conductive paste portion in the third hole and a fourth conductive paste portion in the fourth hole, wherein the third conductive paste portion and the fourth conductive paste portion are both electrically connected to the first conductive circuit layer; The preparation of the intermediate comprises: Fixing the reinforcing member to the third conductive paste portion, wherein the reinforcing member is a conductive member; In the step of folding the second region, the fourth conductive paste portion is connected to a surface of the reinforcing member facing away from the third conductive paste portion.

4. The method for preparing a rigid-flexible circuit board according to claim 2, wherein: The preparation of the circuit unit further includes: forming a covering layer covering the first conductive circuit layer on the substrate; forming a release film layer on the second conductive circuit layer, covering at least the first circuit area and the second circuit area, wherein the release film layer is located in the first area and the third area; forming a first through hole penetrating the release film layer, the first circuit area, and the substrate layer in the first region, and forming a second through hole penetrating the release film layer, the second circuit area, and the substrate layer in the third region; forming the first conductive paste portion in the first through hole and forming the second conductive paste portion in the second through hole; removing the release film layer so that the first through hole forms the first hole and the second through hole forms the second hole; Wherein, in the step of hot pressing the folded substrate, the covering layers located on both sides of the cavity move toward the cavity to be fixed in the groove.

5. The method for preparing a rigid-flexible circuit board according to claim 2, wherein: In the step of folding the second region, the sidewall of the opening is spaced apart from the second conductive paste portion; In the step of pressing the folded substrate, both the first conductive paste portion and the second conductive paste portion are filled in the opening.

6. A rigid-flexible circuit board, characterized in that: The rigid-flexible circuit board includes a circuit unit, a reinforcement member and a dielectric layer; The circuit unit includes a substrate, wherein an extension direction of the substrate is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction. The substrate is divided into a first region, a second region, and a third region connected in sequence in the first direction. The substrate includes a first conductive circuit layer, a base material layer, and a second conductive circuit layer stacked in sequence in the second direction. The second conductive circuit layer includes a first circuit area provided in the first region. The reinforcing member is fixed to the base material layer in the second region, and is spaced apart from both the first region and the third region in the first direction. The second region of the substrate is folded around the reinforcing member, and the third region is stacked on one side of the first region. The dielectric layer is connected between the first region and the third region and covers the first circuit area. The two parts of the substrate located between the reinforcing piece and the dielectric layer are bent toward the second conductive circuit layer and connected to each other to form two grooves away from each other. The grooves are located between the dielectric layer and the reinforcing piece.

7. The rigid-flex circuit board according to claim 6, wherein: The second conductive circuit layer further includes a second circuit area provided in the third region, the dielectric layer is connected between the first circuit area and the second circuit area, and the substrate is provided with a first hole penetrating the first circuit area and the base material layer, and a second hole penetrating the base material layer and the second circuit area; The circuit unit further includes a first conductive paste portion fixed to the first hole and electrically connecting the first circuit area and the first conductive circuit layer, and a second conductive paste portion fixed to the second hole and electrically connecting the second circuit area and the first conductive circuit layer, the first conductive paste portion being protruded from the first circuit area away from the first conductive circuit layer, and the second conductive paste portion being protruded from the second circuit area away from the first conductive circuit layer; The dielectric layer is provided with an opening, and the first conductive paste portion and the second conductive paste portion are both filled in the opening and are electrically connected.

8. The rigid-flex circuit board according to claim 6, wherein: A third hole and a fourth hole are provided in the second region, each of the third hole and the fourth hole passes through the substrate layer. The circuit unit further includes a third conductive paste portion fixed to the third hole and a fourth conductive paste portion fixed to the fourth hole. The third conductive paste portion is located between the first circuit region and the fourth conductive paste portion. The reinforcing member is a conductive member and is electrically connected between the third conductive paste portion and the fourth conductive paste portion.

9. The rigid-flex circuit board according to any one of claims 6 to 8, wherein: The rigid-flexible circuit board further includes a covering layer, and the covering layer covers the first conductive circuit layer.

10. The rigid-flex circuit board according to claim 9, wherein: The covering layer is provided with a window, and the window exposes a portion of the first conductive circuit layer outside the groove.

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