Pure glue and prepreg same-layer mixed pressing rigid-flex printed circuit board and preparation method thereof

Abstract

The invention discloses a rigid-flexible combined board formed by mixing and pressing pure glue and prepregs on the same layer. The rigid-flexible combined board comprises a flexible base material and the prepregs which are sequentially and alternately overlapped, the rigid-flex board is divided into a rigid area and a flexible area along the surface extension direction, and the flexible area can be bent relative to the rigid area; the semi-cured layer comprises at least one mixed layer, the mixed layer comprises a semi-cured part located in the rigid area, and the rest part is a pure glue part. According to the rigid area of the rigid-flexible combined board, full filling of the buried hole and the interlayer gap is realized through high fluidity of the semi-cured part, and board explosion caused by bubble expansion at a subsequent SMT high temperature is avoided; the flexible area retains excellent flexibility through the pure glue part, the requirement for repeated bending of folding equipment is met, and the problem that in the prior art, hole filling reliability and bending performance cannot be considered at the same time through a single material is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of circuit board, and particularly relates to a rigid-flex combined board with pure glue and prepreg in the same layer and a preparation method thereof. BACKGROUND

[0002] With the rapid iteration of mobile communication technology and terminal product form, folding mobile phones as emerging technology products have rapidly risen and become a market hotspot. When unfolded, folding mobile phones can provide a large-screen display experience close to that of a tablet computer, meeting the needs of users for immersive viewing, high-definition gaming, and large-screen browsing. When folded, the volume is similar to that of an ordinary mobile phone, making it easy to carry around, perfectly balancing the immersive experience of a large screen and portability, and effectively solving the pain point of the inconvenience of carrying traditional large-screen electronic devices. At the same time, the large screen after unfolding supports multi-task split-screen function, and users can run multiple applications at the same time, such as viewing documents while replying messages, conducting video conferences while checking data, etc., greatly improving the efficiency of office work and daily use.

[0003] To realize the complex functions and compact form of folding mobile phones, a high-density and high-reliability signal transmission carrier is needed inside. Due to the extremely limited space inside the mobile phone, the signal transmission components not only need to meet the requirements of small size and thinness, but also need to adapt to repeated bending in folding actions, while bearing the installation and fixation of various electronic devices. Rigid-flex combined boards become the core solution for this scenario due to their unique advantages. The flexible part can realize repeated bending at any angle, adapting to the opening and closing actions of folding mobile phones. The rigid part has sufficient structural hardness and can stably bear chips, connectors and other electronic devices, effectively solving the spatial contradiction between signal transmission and device bearing inside folding mobile phones.

[0004] However, existing rigid-flex combined board technology still has significant defects in adapting to the high-precision and high-reliability requirements of folding mobile phones. On the one hand, the outer double-layer flexible board of existing rigid-flex combined boards is mostly directly processed from double-sided flexible substrate. Limited by the substrate structure and processing technology, it is difficult to realize the buried hole design of the secondary outer layer, and it is difficult to meet the high-density interlayer signal transmission requirements of folding mobile phones. On the other hand, if a rigid-flex combined board with double-layer outer flexible board and buried holes in the secondary outer layer is needed, existing technology can only use pure glue as an adhesive to bond two single-sided flexible boards to form a double-layer flexible board. If prepreg is used as an adhesive, although the bonding strength can be improved, the flexible board will lose its bending performance and cannot adapt to folding actions. When pure glue is used for bonding, its flowability and filling capacity are insufficient, and it is difficult to completely fill the buried holes in the hard plate area. In the high-temperature environment of subsequent SMT processing, the bubbles remaining in the holes will expand due to heat, which can easily cause the rigid-flex combined board to explode, seriously affecting the reliability and service life of the product. SUMMARY

[0005] The present application aims to provide a rigid-flexible combined board with pure glue and prepreg mixed in the same layer and a preparation method thereof, so as to solve the technical problems that the existing rigid-flexible combined board loses the bending performance of the flexible area when using the prepreg for adhesion to achieve the design of the secondary outer layer buried hole, and the rigid area is easy to cause the board to burst during SMT when using pure glue for adhesion.

[0006] To achieve the above-mentioned purpose, the specific technical scheme of the rigid-flexible combined board with pure glue and prepreg mixed in the same layer and the preparation method thereof is as follows:

[0007] A rigid-flexible combined board with pure glue and prepreg mixed in the same layer comprises flexible substrates and prepreg layers which are alternately stacked in sequence; the rigid-flexible combined board is divided into a rigid area and a flexible area along the surface extension direction, and the flexible area can be bent relative to the rigid area.

[0008] The prepreg layer comprises at least one mixed layer, and the mixed layer comprises a prepreg part in the rigid area and a pure glue part.

[0009] As a further improvement of the present application, the rigid-flexible combined board comprises single-sided flexible substrates arranged on the upper and lower two sides, and prepreg layers and double-sided flexible substrates which are alternately stacked in sequence between the single-sided flexible substrates.

[0010] As a further improvement of the present application, the prepreg layer is in the rigid area except the mixed layer.

[0011] As a further improvement of the present application, the double-sided flexible substrates are connected through buried holes, and the single-sided flexible substrates and the double-sided flexible substrates are connected through blind holes.

[0012] As a further improvement of the present application, the rigid area comprises a part of area of a first single-sided flexible substrate, a mixed layer and a first double-sided flexible substrate which are stacked in sequence, and a first prepreg layer, a second double-sided flexible substrate, a second prepreg layer and a second single-sided flexible substrate; the flexible area comprises a remaining area of the first single-sided flexible substrate, the mixed layer and the first double-sided flexible substrate which are stacked in sequence relative to the rigid area; the first single-sided flexible substrate comprises a first single-sided flexible substrate rigid part in the rigid area and a first single-sided flexible substrate flexible part in the flexible area, and the first double-sided flexible substrate comprises a first double-sided flexible substrate rigid part in the rigid area and a first double-sided flexible substrate flexible part in the flexible area.

[0013] As a further improvement of the present application, the prepreg part of the mixed layer is recessed inward by 0.1 mm relative to the edge of the rigid area.

[0014] A preparation method of a rigid-flexible combined board with pure glue and prepreg mixed in the same layer comprises the following steps:

[0015] S1, material preparation before first lamination: cleaning pretreatment, circuit pattern transfer and etching, size trimming and quality detection on double-sided flexible substrate, then through positioning hole processing, surface roughening and deep cleaning to improve interlayer adhesion, to get the double-sided flexible substrate to be laminated;

[0016] Adapted pretreatment is performed on the prepreg, and through cutting size, film sticking, matching drilling, and laser reshaping, the prepreg to be laminated is obtained;

[0017] S2, first lamination: after the double-sided flexible substrate and the prepreg are alternately stacked and fixed by rivets, the whole is laminated, size trimming, copper thickness adjustment, positioning and manufacturing of buried and blind holes are performed, hole channel conductive treatment is performed, copper plating is performed on the buried and blind holes to complete the interlayer circuit communication, and the intermediate core layer is obtained after the circuit is manufactured;

[0018] S3, material preparation before second lamination: the two outer single-sided flexible substrates are cut to an appropriate size, the blind hole positions are drilled, and the single-sided flexible substrates to be laminated are obtained after cleaning;

[0019] The prepreg is cut to an appropriate size, the blind hole positions are drilled, and the prepreg to be laminated is obtained;

[0020] S4, mixed layer preparation: the prepreg is cut to an appropriate size, the blind hole positions are drilled, and the part located in the flexible area is removed by windowing, and the prepreg part matched with the rigid area size is reserved;

[0021] The pure glue film is cut to an appropriate size, the blind hole positions are drilled, and the part located in the rigid area is removed by windowing, and the pure glue part matched with the flexible area size is reserved, and the pure glue part is attached to the non-circuit surface flexible area of the corresponding single-sided flexible substrate to be laminated;

[0022] S5, second lamination: the single-sided flexible substrate attached with the pure glue part, the intermediate core layer, the prepreg, the single-sided flexible substrate are aligned and laminated in sequence to form a whole, size trimming, copper thickness adjustment, positioning and manufacturing of blind holes are performed, hole channel conductive treatment is performed, copper plating is performed on the blind holes to complete the interlayer circuit communication, and the rigid-flex combined board is obtained.

[0023] As a further improvement of the application, the edge of the pure glue part extends 0.2mm to the rigid area when windowing in S4, and the edge of the prepreg part is retracted 0.1mm when windowing.

[0024] As a further improvement of the application, the through buried hole is obtained by CNC drilling according to X-ray positioning in S2, and the blind hole is obtained by ESI laser; the blind hole of the rigid area is obtained by CO2 laser according to X-ray positioning in S5, and the blind hole of the flexible area is obtained by ESI laser.

[0025] As a further improvement of the present application, the channel conductive treatment in S2 is: removing impurities on the hole wall by plasma degreasing and strong oxidizing chemical water degreasing, micro-etching to enhance adhesion, and depositing a conductive film on the hole wall.

[0026] The channel conductive treatment in S5 is: removing impurities on the hole wall by plasma degreasing, micro-etching to enhance adhesion, and depositing a conductive film on the hole wall.

[0027] Beneficial effects:

[0028] Through the structural design of the mixed layer containing rigid area semi-cured part and flexible area pure glue part, the rigid area realizes sufficient filling of the channel and gap through the high flowability of the semi-cured part, avoiding the SMT high-temperature board explosion problem caused by insufficient pure glue filling in the prior art; the flexible area maintains excellent flexibility through the pure glue part, meeting the repeated bending demand in the folding scene, effectively solving the technical contradiction between "loss of bending of prepreg" and "unreliable pure glue filling".

[0029] The alternating superposition structure of flexible substrate and semi-cured layer adapts to the needs of compact space and folding scene, so that the product not only meets the device bearing strength of the rigid area, but also realizes the lightness, thinness and compactness of the overall structure, which can adapt to the narrow internal space of folding mobile phones and other equipment; at the same time, the reliable bending performance of the flexible area and the structural stability of the rigid area perfectly match the form demand of "unfolding large screen, folding portable" of folding equipment, widening the application scene of rigid-flex combined board. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a structure diagram of a rigid-flex combined board with pure glue and semi-cured sheet mixed in the same layer of the present application.

[0031] Marked in the figure: 1, first single flexible substrate; 21, solidified part; 22, pure glue part; 3, first double flexible substrate; 4, first semi-cured layer; 5, second double flexible substrate; 6, second semi-cured layer; 7, second single flexible substrate; 8, blind hole; 9, buried hole; 10, rigid area; 11, flexible area. DETAILED DESCRIPTION

[0032] In order to better understand the purpose, structure and function of the present application, the present application of a rigid-flex combined board with pure glue and semi-cured sheet mixed in the same layer and its preparation method will be further described in detail below in combination with the drawings.

[0033] Implementation example:

[0034] For example, Figure 1The shown pure glue and prepreg mixed layer laminated rigid-flexible combined board, in this embodiment, is composed of first single-sided flexible substrate 1, mixed layer, first double-sided flexible substrate 3, first semi-cured layer 4, second double-sided flexible substrate 5, second semi-cured layer 6, and second single-sided flexible substrate 7 in sequence. The single-sided flexible substrate is a circuit layer with copper foil on one side of the base material, and the double-sided flexible substrate is a circuit layer with copper foil on both sides of the base material. The circuit layers of the first single-sided flexible substrate 1 and the first double-sided flexible substrate 3 are connected through blind holes 8, and the circuit layers of the first double-sided flexible substrate 3 and the second double-sided flexible substrate 5 are connected through buried holes 9. The rigid-flexible combined board is divided into rigid area 10 and flexible area 11 from left to right along the surface, and the mixed layer is composed of semi-cured part 21 and pure glue part 22, which are located in the rigid area 10 and the flexible area 11 respectively. Part of the first single-sided flexible substrate 1 and the first double-sided flexible substrate 3 is located in the rigid area 10, and the other part is located in the flexible area 11. The first semi-cured layer 4, the second double-sided flexible substrate 5, the second semi-cured layer 6, and the second single-sided flexible substrate 7 are all located in the rigid area 10. The board material located in the flexible area 11 can be bent and turned over relative to the rigid area 10.

[0035] The preparation method of the pure glue and prepreg mixed layer laminated rigid-flexible combined board specifically includes the following steps:

[0036] Step one, pretreat the first double-sided flexible substrate 3 and the second double-sided flexible substrate 5. The double-sided flexible substrate uses polyimide film as the base material, and copper foil is compounded on both sides of the film. The surface of the substrate is cleaned with an alkaline solution to remove oil stains and oxidation layers. A photosensitive dry film is attached to both sides of the substrate, and the circuit pattern is transferred to the dry film through an exposure machine. The inner layer circuit is etched through the DES process. The substrate is cut according to the design size, and the circuit integrity is detected by the AOI automatic optical detection equipment. The rivet holes are cut on the edge of the substrate using a laser cutting machine. The substrate is immersed in a brown solution and reacted under suitable conditions to form a rough brown oxidation film on the copper surface. The surface residual organic matter is removed by a plasma cleaning machine, and the completed substrate is temporarily stored in the false stacking area.

[0037] Pretreat the first semi-cured layer 4. Select a semi-cured sheet of glass fiber cloth impregnated with epoxy resin, and cut it according to the design specifications. Attach a back-loaded film to one side of the semi-cured sheet to prevent adhesion. Use a numerical control drilling machine to drill rivet holes that match the double-sided flexible substrate. Use a laser cutting machine to trim the edges to ensure that the size matches the double-sided flexible substrate. After completion, the semi-cured layer is temporarily stored in the false stacking area.

[0038] Step two, first lamination, the first double-sided flexible substrate 3, the first semi-cured layer 4, the second double-sided flexible substrate 5 are stacked in order, and the positioning and fixing are realized by rivets passing through the rivet holes to ensure that the alignment accuracy of each layer meets the design requirements. Put the false stack into the vacuum laminator and set the appropriate lamination parameters; during the lamination process, the epoxy resin of the first semi-cured layer melts and flows to fill the buried holes and gaps between the two double-sided flexible substrates, and after cooling and solidification, the intermediate core layer is formed.

[0039] The subsequent processing of the intermediate core layer includes the following in turn:

[0040] Edge milling: use a numerical control milling machine to cut off the redundant edge frame of the intermediate core layer and trim it to the design specification;

[0041] Copper reduction: use a micro-etching solution to reduce the thickness of the outer copper layer to the design value;

[0042] X-ray positioning: identify the substrate positioning marks through an X-ray detection device to determine the drilling coordinates;

[0043] CNC drilling: drill through the intermediate core layer;

[0044] Film removal: remove the residual back-loaded film;

[0045] Deburring: use a sandblasting process to remove the hole burrs;

[0046] ESI laser blind drilling: use an ESI laser processing machine to make blind holes on the surface circuit layer of the first double-sided flexible substrate facing the first single-sided flexible substrate;

[0047] Plasma degreasing: use a plasma cleaning machine to remove the hole residue;

[0048] Desmear: soak in potassium permanganate solution to thoroughly remove residual organic matter on the hole wall;

[0049] Post-blind hole micro-etching: micro-etching solution treatment to form a rough surface on the hole wall;

[0050] Blind hole AOI sampling inspection: sampling inspection to ensure that the blind hole is not blocked and the hole position is accurate;

[0051] Black shadow: deposit a conductive film on the hole wall;

[0052] Blind hole AOI: full inspection of the hole wall conductive film coverage integrity;

[0053] Copper plating: first chemical copper plating, then electrolytic copper plating, to form a continuous copper layer on the hole wall and the outer copper surface, realizing the electrical connection of the buried hole and the blind hole;

[0054] Outer layer processing: clean and cover with dry film, and make outer layer circuit through exposure and DES process;

[0055] AOI detection: all the outer layer circuits are defect-free;

[0056] Brown: treated with brown solution to form an oxide film; after completion, transfer to the false stacking area for temporary storage.

[0057] Step three, pretreat the first single-sided flexible substrate 1 and the second single-sided flexible substrate 7, select the single-sided flexible substrate of the PI film single-sided composite copper foil, cut according to the design specifications; use a numerical control drilling machine to drill through holes corresponding to the blind holes in the middle core layer; after cleaning with an alkaline solution, use an ion cleaning machine for treatment, and transfer to the false stacking area for temporary storage.

[0058] Pretreat the second semi-cured layer 6, select a semi-cured sheet, and cut according to the design specifications; use a numerical control drilling machine to drill matching hole positions; use a laser to open a window to remove the corresponding part of the flexible area, and transfer to the false stacking area for temporary storage.

[0059] Step four, pretreat the semi-cured part 21 of the mixed layer, select a semi-cured sheet, and cut it to a size matching the middle core layer substrate, serving as the "rigid area glue" of the outer layer; use a numerical control drilling machine to drill hole positions matching the middle core layer; open a window and cut off the part in the flexible area 11, and inwardly shrink the edge of the rigid area 10 by 0.1 mm, with an overlap of 0.1 mm with the 0.2 mm extension of the pure glue part 22, to ensure that there is no gap in the boundary area and that the lamination is more secure.

[0060] Pretreat the pure glue part 22 of the mixed layer, select an epoxy resin pure glue film, cut the pure glue film to a basic size suitable for the flexible area, and use it as the "flexible area glue"; use a numerical control drilling machine to drill hole positions matching the middle core layer; use a laser to open a window to remove the corresponding part of the rigid area 10, leaving only the pure glue film in the flexible area, but extending the pure glue edge by 0.2 mm towards the rigid area, overlapping with the semi-cured part 21 at the boundary area, to prevent "glue deficiency" due to alignment deviation from causing interlayer separation. Place the pretreated pure glue part back-to-back with the non-circuit side of the first single-sided flexible substrate, and transfer to the false stacking area for temporary storage after ion cleaning.

[0061] Step five, second lamination: in order, laminate the first single-sided flexible substrate 1 with the pure glue part 22, the semi-cured part 21 of the mixed layer (the non-circuit side of the first single-sided flexible substrate 1 is laminated), the middle core layer, the second semi-cured layer 6, and the second single-sided flexible substrate 7, ensuring that the semi-cured part 21 of the mixed layer overlaps with the pure glue part 22 at the boundary area. Place it in a vacuum laminator and use staged lamination parameters; during the lamination process, the semi-cured part of the rigid area 10 melts to fill the gap, and the pure glue part of the flexible area 11 solidifies to maintain flexibility, forming a rigid-flex combination board after cooling and solidification.

[0062] The post-processing procedures for the laminated rigid-flex combination board include the following steps in order:

[0063] Trimming: cutting off the redundant part of the edge to trim to the finished product size;

[0064] Copper reduction: reducing the outer layer of copper to the designed thickness;

[0065] X-ray positioning: determining the outer layer blind hole processing coordinates;

[0066] Brown: forming an oxide film by treating with a brown solution;

[0067] CO2 laser blind hole: using CO2 laser to make the blind hole of the rigid area;

[0068] CNC drilling: drilling the finished product mounting hole according to the X-ray positioning coordinates;

[0069] Deburring: removing the burr of the hole;

[0070] Desmear: opening ultrasonic assistance and soaking in potassium permanganate solution;

[0071] ESI laser blind hole: using ESI laser to make the blind hole of the flexible area;

[0072] Plasma degreasing: treating with a plasma cleaning machine;

[0073] Post-blind hole micro-etching: treating with a micro-etching solution;

[0074] Blind hole AOI sampling inspection: sampling inspection according to the proportion;

[0075] Black shadow: depositing a conductive film;

[0076] Blind hole AOI: full inspection;

[0077] Copper plating: first chemical copper plating, then electrolytic copper plating, forming a continuous copper layer on the hole wall and the outer layer of copper surface, realizing the electrical connection of the blind hole;

[0078] Outer layer pretreatment: cleaning and roughening before making the outer layer circuit, finally obtaining the finished product rigid-flex combined board.

[0079] The rigid-flex combined board prepared in this embodiment has sufficient buried hole filling in the rigid area, and no board explosion phenomenon occurs in subsequent processing; the flexible area has excellent bending resistance, the interlayer bonding force meets the use requirements, and can adapt to the application scenarios of folding electronic equipment.

[0080] The application is designed by mixing the rigid area of the semi-cured part of the layer and the flexible area of the pure glue part, so that the rigid area realizes the full filling of the hole and gap by the flow characteristics of the semi-cured sheet, avoiding the risk of board explosion in subsequent processing; the flexible area retains excellent flexibility through the pure glue part, meeting the repeated bending requirements of folding equipment, and completely solving the technical problems of "insufficient hole filling of pure glue" and "loss of bending of semi-cured sheet". The overlapping design of the pure glue part extending to the rigid area and the semi-cured part shrinking inward eliminates the gap between the rigid area and the flexible area, avoids the lack of glue problem caused by alignment deviation during lamination, significantly improves the interlayer bonding force, and guarantees the structural stability of the product in long-term use.

[0081] It can be understood that the present application is described by some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the present application. In addition, under the guidance of the present application, these features and embodiments can be modified to adapt to specific conditions and materials without departing from the spirit and scope of the present application. Therefore, the present application is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application are within the scope of the present application.

Claims

1. A rigid-flex PVC board with a co-layer of pure adhesive and prepreg, characterized in that, It includes a flexible substrate and a semi-cured layer that are stacked alternately in sequence; the rigid-flex plate is divided into a rigid region and a flexible region along the surface extension direction, and the flexible region can be bent relative to the rigid region; The semi-cured layer includes at least one mixed layer, which includes a semi-cured portion located in the rigid region and a pure adhesive portion as the remainder.

2. The rigid-flex PVC board with pure adhesive and semi-cured sheet co-layered as described in claim 1, characterized in that, It includes a single-sided flexible substrate disposed on the upper and lower surfaces, and a semi-cured layer and a double-sided flexible substrate alternately stacked between the single-sided flexible substrate.

3. The rigid-flex PVC board with pure adhesive and prepreg co-layered pressing according to claim 2, characterized in that, Except for the hybrid layer, all the semi-cured layers are located within the rigid region.

4. The rigid-flex PVC board with pure adhesive and prepreg co-layered pressing according to claim 2, characterized in that, The double-sided flexible substrates are connected by buried vias, and the single-sided flexible substrate and the double-sided flexible substrate are connected by blind vias.

5. The rigid-flex PVC board with pure adhesive and semi-cured sheet co-layered as described in claim 2, characterized in that, The rigid region includes a portion of a first single-sided flexible substrate, a hybrid layer, and a first double-sided flexible substrate stacked sequentially, as well as a first semi-cured layer, a second double-sided flexible substrate, a second semi-cured layer, and a second single-sided flexible substrate; the flexible region includes the remaining portion of the first single-sided flexible substrate, the hybrid layer, and the first double-sided flexible substrate stacked sequentially relative to the rigid region; the first single-sided flexible substrate includes a rigid portion of the first single-sided flexible substrate located in the rigid region and a flexible portion of the first single-sided flexible substrate located in the flexible region, and the first double-sided flexible substrate includes a rigid portion of the first double-sided flexible substrate located in the rigid region and a flexible portion of the first double-sided flexible substrate located in the flexible region.

6. The rigid-flex PVC board with pure adhesive and prepreg co-layered pressing according to claim 3, characterized in that, The semi-cured portion of the hybrid layer is recessed 0.1 mm from the edge of the rigid region.

7. A method for preparing a rigid-flexible composite board with pure adhesive and prepreg co-layered pressing as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Material preparation before the first lamination: Cleaning and pretreatment of the double-sided flexible substrate, circuit pattern transfer and etching, dimensional trimming and quality inspection, and then improving the interlayer adhesion through positioning hole processing, surface roughening and deep cleaning to obtain the double-sided flexible substrate to be laminated. Pre-treatment of the prepreg is carried out by cutting the size, applying anti-stick film, matching drilling, and laser shaping to obtain the prepreg layer to be laminated; S2, First lamination: After alternatingly stacking double-sided flexible substrate and prepreg by rivets, the substrate is laminated into a whole. After size trimming and copper thickness adjustment, buried and blind vias are positioned and fabricated. The vias are then conductively treated. Copper plating is applied to the buried and blind vias to complete the interlayer circuit connection. After the circuit is fabricated, the middle core layer is obtained. S3. Material preparation before the second lamination: Cut the single-sided flexible substrate on both sides to the appropriate size, drill holes to match the blind hole positions, and clean to obtain the single-sided flexible substrate to be laminated. Cut the prepreg to the appropriate size, drill holes to match the blind hole positions, and obtain the prepreg layer to be laminated; S4. Preparation of the hybrid layer: Cut the prepreg to the appropriate size, drill holes to match the blind hole positions, open windows to remove the part located in the flexible area, and retain the prepreg part that matches the size of the rigid area. Cut the pure adhesive film to the appropriate size, drill holes to match the blind hole positions, open windows to remove the part located in the rigid area, retain the pure adhesive part that matches the size of the flexible area, and attach the pure adhesive part to the non-circuit flexible area of ​​the corresponding single-sided flexible substrate to be laminated. S5. Second lamination: Align and stack the single-sided flexible substrate, semi-cured part, intermediate core layer, semi-cured layer and single-sided flexible substrate in sequence to form a whole. After size trimming and copper thickness adjustment, blind holes are made in the positioning, and the channels are made conductive. Copper is plated on the blind holes to complete the interlayer circuit connection, and a rigid-flex board is obtained.

8. The method for preparing a rigid-flexible bonded plate with pure adhesive and prepreg co-layered as described in claim 7, characterized in that, When the window is opened in S4, the edge of the pure glue part extends 0.2mm toward the rigid area, and the edge of the semi-cured part retracts 0.1mm when the window is opened.

9. The method for preparing a rigid-flex PVC board with pure adhesive and prepreg co-layered pressing according to claim 7, characterized in that, In S2, CNC drilling is used to obtain through-holes based on X-ray positioning, and ESI laser is used to create blind holes; in S5, CO2 laser is used to create blind holes in the rigid area based on X-ray positioning, and ESI laser is used to create blind holes in the flexible area.

10. The method for preparing a rigid-flex PVC board with pure adhesive and prepreg co-layered pressing according to claim 7, characterized in that, The conductive treatment of the S2 channel is as follows: impurities on the hole wall are removed by plasma degumming and strong oxidizing solution degumming, micro-etching enhances adhesion, and a conductive film is deposited on the hole wall. The conductive treatment of the S5 channel is as follows: plasma degumming removes adhesive residue to clean impurities from the hole wall, micro-etching enhances adhesion, and a conductive film is deposited on the hole wall.

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