Rigid-flex board
By using medium-flow PP sheets and layering barrier adhesives in rigid-flex boards, the problem of adhesive overflow during high-temperature lamination was solved, enabling thinner multilayer circuit board designs and simplified process flows.
Patent Information
- Application Number
- CN202422639418.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2034-10-31
AI Technical Summary
Traditional rigid-flex PCBs are prone to adhesive overflow during high-temperature lamination, and existing improvement methods such as pre-embedded copper blocks and filler gaskets have problems of high material costs and complex processes.
A medium-flow PP sheet is used, with a barrier adhesive layered in between. The barrier adhesive has a higher melting point than the medium-flow PP sheet and prevents adhesive overflow through adhesion. Combined with the flexibility and high-temperature stability of the PI film, the lamination structure is optimized to control the overall thickness.
It effectively reduces adhesive overflow in the cutout area, simplifies the process, reduces material costs, and enables thinner multilayer circuit board designs.
Smart Images
Figure CN223528276U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the preparation technical field of rigid-flex board, in particular to a rigid-flex board. BACKGROUND
[0002] The rigid-flex board can be used in some products with special requirements, which has a certain flexure area and a certain rigid-flex area, and is helpful for saving internal space of the product, reducing the size of the finished product and improving the performance of the product.
[0003] In the manufacturing process of the traditional rigid-flex board, the PP sheet corresponding to the flexure area is first windowed, then the flexible core plate and the outer copper foil are combined together through pressing, and the hollow area located at the windowed position of the PP layer is formed. Since the side wall of the hollow area is prone to overflow during the high-temperature pressing process, in order to solve the overflow problem of the hollow area in the traditional process, the PP sheet is usually made of low-flow PP sheet. Since the low-flow PP sheet has poor flowability during the pressing process, a relatively thick glue is needed to fill the gap between the layers, and the overall thickness of the rigid-flex board cannot be reduced during the layering. In the prior art, the overflow is improved by using medium-flow PP sheet and embedding copper blocks or filling shims in the hollow area. However, although the copper blocks can improve the overflow, they need to be made according to the size of the specific hollow area before pressing, and the material cost and processing cost of the copper blocks are very high. When the copper blocks are taken out after pressing, it is also difficult to disassemble. In the filling shim process, the material performance of the shim is required to be higher, and it is difficult to ensure that the structure is still stable in a high-temperature environment and achieves the expected overflow and blocking effect. CONTENT OF THE UTILITY MODEL
[0004] To solve the above technical problems, the utility model provides a rigid-flex board, which optimizes the layering structure, reduces the overflow of the hollow area during the high-temperature pressing process, and improves the overall performance.
[0005] The technical scheme of the utility model is as follows: a flexible core plate, an inner copper foil and a cover film are sequentially layered on the flexible core plate, the flexible core plate includes a flexure area A and a rigid-flex area B, a medium-flow PP sheet that has been windowed and an outer copper foil are sequentially layered on the rigid-flex area B, and a hollow area located at the windowed position of the medium-flow PP sheet is formed; a barrier glue is layered between the cover film and the medium-flow PP sheet, the surface of the barrier glue has good adhesion, and the melting point of the barrier glue is higher than that of the medium-flow PP sheet.
[0006] Further, the outer copper foil, the medium-flow PP sheet, the barrier glue, the cover film and the inner copper foil are symmetrically distributed on the corresponding upper and lower surfaces of the flexible core plate.
[0007] Further, the rigid-flex area B is distributed on the opposite sides of the flexure area A.
[0008] Further, the flexible core plate adopts a PI film, which enables the flexible core plate in the flexure area A to bear bending and deformation.
[0009] Further, the part of the outer layer copper foil corresponding to the flexure area A is removed through a graphic etching process.
[0010] Further, the thickness of the barrier glue is designed as 5-6 microns.
[0011] The beneficial technical effects of the utility model are as follows: the barrier glue and the middle flow glue PP sheet are reasonably laminated in the rigid-flex combined plate, so that the overall thickness of the rigid-flex combined plate can be effectively controlled when the layers are increased; the overflow glue condition of the hollow area in the laminating process is greatly improved; meanwhile, the barrier glue also avoids subsequent complex processing technology, and is flexible and convenient to use. BRIEF DESCRIPTION OF DRAWINGS
[0012] Figure 1 is the overall structure schematic view of the utility model;
[0013] Figure 2 is the overflow glue schematic view produced when laminating without laminating the barrier glue;
[0014] Figure 3 is the overflow glue schematic view produced when laminating with laminating the barrier glue;
[0015] Among them: A, flexure area; B, rigid-flex combined area;
[0016] 1, flexible core plate; 2, inner layer copper foil; 3, cover film; 4, middle flow glue PP sheet; 5, outer layer copper foil; 6, barrier glue; 7, overflow glue. DETAILED DESCRIPTION
[0017] In order to more clearly understand the technical means of the utility model, and can be implemented according to the content of the specification, the specific embodiments of the utility model are further described in detail below, the following examples are used to illustrate the utility model, but not to limit the scope of the utility model.
[0018] Refer to Figure 1The utility model provides a rigid flexible combination board, including flexible core board 1 and flexible core board 1 upper and lower surface's inner layer copper foil 2, the windowed middle flow glue PP piece 4. Flexible core board 1 includes flexure area A and the rigid flexible combination area B distributed in the opposite sides of bending area, the rigid flexible combination area B is successively laminated middle flow glue PP piece 4 and outer layer copper foil 5 on, and forms the hollow area in the windowed position of middle flow glue PP piece 4, the flow glue of middle flow glue PP piece 4 forms better flowability under high temperature, to satisfy the flow glue of laminating and can be efficiently filled in the interstice of layer, to better control the thickness of rigid flexible combination board, especially when rigid flexible combination board is multilayer circuit board design, uses middle flow glue PP piece 4 and can reach better interlayer connection effect and thinner multilayer circuit board laminated structure.
[0019] In the embodiment, the flexible core board 1 adopts PI film, which is also known as polyimide film. The polyimide film can not be deformed or degraded under high temperature, has excellent thermal stability, chemical resistance and mechanical properties, and at the same time, has good insulation performance and flexibility, so that the flexible core board 1 located in the flexure area A can withstand bending and deformation.
[0020] The covering film 3 is arranged between the inner layer copper foil 2 and the middle flow glue PP piece 4, and provides additional protection for the inner layer copper foil 2, prevents the inner layer copper foil 2 from being scratched, oxidized or contaminated during processing, and at the same time, helps to improve the electrical insulation performance and bonding strength.
[0021] During manufacturing, first, the inner layer circuit is manufactured on the inner layer copper foil 2, the covering film 3, the inner layer copper foil 2, the flexible core board 1, the inner layer copper foil 2 and the covering film are sequentially stacked from top to bottom, and then the covering film 3 is completely bonded with the inner layer copper foil 2 and the flexible core board 1 by rapid pressing to form a primary pressing board; second, the windowed middle flow glue PP piece 4 and the outer layer copper foil 5 are sequentially laminated on the upper and lower surfaces of the primary pressing board corresponding, and a secondary pressing board is manufactured by secondary pressing under high temperature and high pressure, and then the outer layer circuit is manufactured on the outer layer copper foil 5.
[0022] Due to the use of the middle flow glue PP piece 4 and the secondary pressing under high temperature and high pressure, the flow glue formed by the middle flow glue PP piece 4 under high temperature has good flowability, and the overflow glue 7 of the side wall of the hollow area is likely to occur during the secondary pressing, as shown in FIG. 6. Figure 2 In the embodiment, the barrier glue 6 is laminated between the covering film 3 and the middle flow glue PP piece 4, the surface of the barrier glue 6 is made of a material with good adhesion and toughness, and the melting point of the barrier glue 6 is higher than that of the middle flow glue PP piece 4.
[0023] The whole laminated structure is put into a laminating machine after being pre-laminated according to laminating requirements to be laminated at high temperature and high pressure. During the laminating process, the flow glue PP sheet 4 formed at high temperature fills the gap between the layers and forms a firm interlayer connection. At the same time, due to the existence of the barrier glue 6, the outer copper foil 5 is adhered to the barrier glue 6 in the hollow area during laminating, and the adhesion between the outer copper foil 5 and the barrier glue 6 reduces the flow glue from flowing into the hollow area, thereby playing a role of blocking the overflow glue 7, such as Figure 3 At the same time, the adhesion of the barrier glue 6 effectively prevents the flow glue from flowing into the hollow area during the laminating process, thereby further improving the overflow glue 7.
[0024] In this embodiment, in order to ensure that the barrier glue 6 does not affect the thickness of the whole rigid-flexible combined board, the thickness of the barrier glue 6 is designed to be 5-6 μm.
[0025] After the laminated structure of the multilayer circuit board is laminated at high temperature and high pressure, the dry film protection pattern area is used to expose the outer copper foil 5 above the corresponding position of the flexible area A, and then the exposed outer copper foil 5 is removed through a pattern etching process to realize the required circuit structure and complete the production of the rigid-flexible combined board.
[0026] The preferred embodiments of the present application are described above, and the present application is not limited to the above. It should be pointed out that, for ordinary skilled persons in the technical field, some improvements and modifications can be made without departing from the technical principles of the present application, and these improvements and modifications should also be regarded as the protection scope of the present application.
Claims
1. A rigid-flex board, comprising a flexible core board (1) and an inner copper foil (2) and a cover film (3) sequentially stacked on the flexible core board (1), wherein the flexible core board (1) includes a flexural region A and a rigid-flex bonding region B, and a windowed mid-flow adhesive PP sheet (4) and an outer copper foil (5) are sequentially stacked on the rigid-flex bonding region B, forming a hollow area located at the windowed position of the mid-flow adhesive PP sheet (4); characterized in that: The covering film (3) is laminated with the barrier glue (6) between the middle flow glue PP sheet (4), the surface of the barrier glue (6) has good adhesion and the melting point of the barrier glue (6) is higher than the melting point of the middle flow glue PP sheet (4).
2. The rigid-flex printed circuit board of claim 1, wherein: The outer layer copper foil (5), the middle flow glue PP sheet (4), the barrier glue (6), the covering film (3) and the inner layer copper foil (2) are symmetrically distributed on the upper and lower surfaces of the flexible core plate (1) with the flexible core plate (1) as the center.
3. The rigid-flex printed circuit board of claim 1, wherein: The rigid-flexible combination area B is distributed on the opposite sides of the bending area A.
4. The rigid-flex printed circuit board of claim 1, wherein: The flexible core plate (1) adopts a PI film, so that the flexible core plate (1) can bear bending and deformation in the bending area A.
5. The rigid-flex printed circuit board of claim 1, wherein: The part of the outer layer copper foil (5) corresponding to the bending area A is removed by a graphic etching process.
6. The rigid-flex printed circuit board of claim 1, wherein: The thickness of the barrier glue (6) is designed to be 5-6 microns.