High-bendability flexible circuit board

Abstract

The utility model relates to the technical field of flexible circuit boards, in particular to a high-bendability flexible circuit board, which comprises a copper foil, a first adhesive layer, an aluminum honeycomb core, a second adhesive layer and a PI (Polyimide) layer, the upper and lower sides of the copper foil are fixedly connected with the aluminum honeycomb core through the first adhesive layer, so that the copper foil can be matched with the bending of the circuit board, the fracture resistance of the circuit board is improved, and the service life of the circuit board is prolonged. The bending life of the flexible circuit board is prolonged, through the aluminum honeycomb core, not only can the pressure resistance and fracture resistance of the flexible circuit board be improved, but also the heat dissipation efficiency of the copper foil can be improved, the flexible circuit board is convenient to use, the composite insulation heat conduction coating and the insulation layer are arranged to play a role in isolating honeycomb aluminum electric conduction from the circuit layer, the short circuit risk is avoided, and the service life of the flexible circuit board is prolonged. The intermediate layer can improve the transfer efficiency of heat from the circuit layer to the honeycomb aluminum, the surface layer is hydrophobic and wear-resistant, the outdoor service life is prolonged, and the comprehensive performance of the ultrathin honeycomb aluminum coating is remarkably improved through the composite insulating heat-conducting coating.

Description

Technical Field

[0001] This utility model belongs to the field of flexible circuit board technology, specifically relating to a highly flexible circuit board with high bending. Background Technology

[0002] Flexible printed circuits (FPCs) are a technology developed in the United States in the 1970s for the development of aerospace rocket technology. They are highly reliable and extremely flexible printed circuits made with polyester film or polyimide as the substrate. By embedding circuit designs into a flexible, thin plastic sheet, a large number of precision components can be packed into narrow and limited spaces, thus forming a flexible circuit. This type of circuit can be bent and folded at will, is lightweight, small in size, has good heat dissipation, and is easy to install, breaking through the limitations of traditional interconnection technologies. The materials that make up the structure of a flexible circuit are insulating film, conductors, and adhesives.

[0003] However, existing flexible circuit boards often have simple structures, poor bending resistance, and lack additional fracture-resistant intermediate layers. They are prone to breakage during use, leading to damage to electrical components and making them inconvenient to use. Therefore, there is an urgent need for a flexible circuit board with high bending resistance to solve the above problems. Utility Model Content

[0004] In order to overcome the above-mentioned technical problems, the purpose of this utility model is to provide a highly flexible circuit board, so as to solve the problem mentioned in the background art that some flexible circuit boards often have simple structures, poor bending resistance, and do not have an additional anti-fracture intermediate layer.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a highly flexible circuit board, comprising copper foil, adhesive layer one, aluminum honeycomb core, adhesive layer two, and PI layer. The upper and lower sides of the copper foil are fixedly connected to the aluminum honeycomb core through adhesive layer one. The top of the aluminum honeycomb core at the top end is fixedly connected to the PI layer through adhesive layer two, and the bottom of the aluminum honeycomb core at the bottom end is fixedly connected to the PI layer through adhesive layer two.

[0006] Preferably, the thickness of the aluminum honeycomb core is 0.05 mm, and the honeycomb pore size of the aluminum honeycomb core is 0.05 mm.

[0007] Preferably, the honeycomb orientation of the aluminum honeycomb core is consistent with the bending direction of the flexible circuit board.

[0008] Preferably, the surface of the aluminum honeycomb core is coated with a composite insulating and thermally conductive coating, which includes an insulating layer, an intermediate layer, and a surface layer.

[0009] Preferably, the insulating layer uses a polyimide solution with a thickness of 5-8 μm.

[0010] Preferably, the intermediate layer uses epoxy resin mixed with silicon carbide nanoparticles, with a thickness of 2-3 μm.

[0011] Preferably, the surface layer uses fluorinated organosilicon with a thickness of 0.5-1 μm.

[0012] Compared with the prior art, the beneficial effects of this utility model are:

[0013] 1. This highly flexible circuit board features an aluminum honeycomb core. When the flexible circuit board bends, the honeycomb holes at the top expand while those at the bottom shrink, thus adapting to the bending of the circuit board and enhancing its fracture resistance and bending lifespan. The honeycomb structure significantly improves the compressive and bending strength of the flexible circuit board, reducing stress fatigue during dynamic bending. The high thermal conductivity of aluminum, combined with the increased honeycomb surface area, improves the heat dissipation efficiency of the circuit board, making it suitable for high-temperature applications such as LED strips and 5G RF modules. The aluminum honeycomb core not only enhances the compressive and fracture resistance of the flexible circuit board but also improves the heat dissipation efficiency of the copper foil, facilitating its use.

[0014] 2. This highly flexible circuit board features a composite insulating and thermally conductive coating. The insulating layer in the composite insulating and thermally conductive coating isolates the conductive honeycomb aluminum from the circuit layer, preventing short-circuit risks. The intermediate layer improves the efficiency of heat transfer from the circuit layer to the honeycomb aluminum. The surface layer is hydrophobic and wear-resistant, extending its outdoor service life. The coating is applied using electrostatic spraying, which oriented the nanoparticles and reduces stress concentration. The composite insulating and thermally conductive coating significantly improves the overall performance of the ultra-thin honeycomb aluminum coating. The thermally conductive design of the insulating layer and intermediate layer balances electrical safety and heat dissipation requirements, while extending the lifespan of the surface layer. Attached Figure Description

[0015] Figure 1 This is a front perspective view of the present utility model;

[0016] Figure 2 This is a schematic diagram of the exploded structure of this utility model;

[0017] Figure 3 This is a schematic diagram of the present invention when bent;

[0018] Figure 4 This is a schematic diagram of the aluminum honeycomb core of this utility model when bent;

[0019] Figure 5 This is a front sectional view of the present invention.

[0020] In the diagram: 1. Copper foil; 2. Adhesive layer one; 3. Aluminum honeycomb core; 4. Adhesive layer two; 5. PI layer. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] Please see Figure 1-5 This utility model provides an embodiment of a highly flexible circuit board, comprising a copper foil 1, an adhesive layer 2, an aluminum honeycomb core 3, an adhesive layer 4, and a PI layer 5. The upper and lower sides of the copper foil 1 are fixedly connected to the aluminum honeycomb core 3 via the adhesive layer 2. The top of the top aluminum honeycomb core 3 is fixedly connected to the PI layer 5 via the adhesive layer 4, and the bottom of the bottom aluminum honeycomb core 3 is fixedly connected to the PI layer 5 via the adhesive layer 4. A stacked design of "flexible substrate PI—insulating aluminum honeycomb core layer—conductive circuit layer" is adopted, with the aluminum honeycomb core serving as the intermediate reinforcing layer. Low-temperature curing epoxy or thermoplastic adhesive is used, and the aluminum honeycomb core is bonded to the PI substrate via a roll forming process to avoid high-temperature damage. Laser cutting of the aluminum honeycomb ensures smooth edges and reduces interference with subsequent etching processes. The aluminum honeycomb core 3 not only improves the compressive strength and fracture resistance of the flexible circuit board but also enhances the heat dissipation efficiency of the copper foil, facilitating its use.

[0023] Furthermore, the aluminum honeycomb core 3 has a thickness of 0.05 mm and a honeycomb aperture of 0.05 mm. The honeycomb structure can significantly improve the compressive and bending strength of the flexible circuit board and reduce stress fatigue during dynamic bending. The high thermal conductivity of aluminum, combined with the increased honeycomb surface area, improves the heat dissipation efficiency of the circuit board, making it suitable for high-temperature scenarios such as LED light strips and 5G RF modules.

[0024] Furthermore, the honeycomb direction of the aluminum honeycomb core 3 is consistent with the bending direction of the flexible circuit board. When the flexible circuit board bends, the honeycomb holes of the top aluminum honeycomb core 3 expand and the honeycomb holes of the bottom aluminum honeycomb core 3 shrink, which can cooperate with the bending of the circuit board and improve the circuit board's anti-breakage performance.

[0025] Furthermore, the surface of the aluminum honeycomb core 3 is coated with a composite insulating and thermally conductive coating, which includes an insulating layer, an intermediate layer, and a surface layer. The composite insulating and thermally conductive coating significantly improves the overall performance of the ultra-thin honeycomb aluminum coating. The thermal conductivity design of the insulating layer and the intermediate layer takes into account both electrical safety and heat dissipation requirements, while the surface layer extends the service life.

[0026] Furthermore, the insulation layer uses a polyimide solution with a thickness of 5-8μm. The insulation layer serves to isolate the conductive layer of the honeycomb aluminum from the circuit layer, avoiding the risk of short circuits. The middle layer uses epoxy resin mixed with silicon carbide nanoparticles with a thickness of 2-3μm. The middle layer can improve the heat transfer efficiency from the circuit layer to the honeycomb aluminum. The surface layer uses fluorinated organosilicon with a thickness of 0.5-1μm. The surface layer is hydrophobic and wear-resistant, extending its outdoor service life.

[0027] Working principle:

[0028] In this application, copper foil 1, adhesive layer 2, adhesive layer 4, and PI layer 5 are all existing technologies, so they will not be elaborated on in detail here. A stacked design of "flexible substrate PI—insulating aluminum honeycomb core layer—conductive circuit layer" is adopted, with the aluminum honeycomb core serving as the intermediate reinforcing layer. Low-temperature curing epoxy or thermoplastic adhesives are used to bond the aluminum honeycomb core to the PI substrate through a roll forming process, avoiding high-temperature damage. Laser cutting of the honeycomb aluminum ensures smooth edges and reduces interference with subsequent etching processes. When the flexible circuit board bends, the honeycomb holes of the top aluminum honeycomb core 3 expand, while the honeycomb holes of the bottom aluminum honeycomb core 3 shrink, thus accommodating the bending of the circuit board and improving its fracture resistance, thereby increasing the bending life of the flexible circuit board. The honeycomb structure significantly improves the compressive and bending strength of the flexible circuit board, reducing the impact of dynamic bending. The high thermal conductivity of aluminum, combined with the increased surface area of ​​the honeycomb structure, improves the heat dissipation efficiency of the circuit board, making it suitable for high-temperature applications such as LED light strips and 5G RF modules. The aluminum honeycomb core not only enhances the compressive strength and fracture resistance of the flexible circuit board but also improves the heat dissipation efficiency of the copper foil, facilitating its use. The insulating layer in the composite insulating thermally conductive coating isolates the conductive layer of the honeycomb aluminum from the circuit layer, preventing short-circuit risks. The intermediate layer improves the efficiency of heat transfer from the circuit layer to the honeycomb aluminum. The surface layer is hydrophobic and wear-resistant, extending its outdoor service life. Electrostatic spraying is used during coating application, ensuring the directional alignment of nanoparticles and reducing stress concentration. The composite insulating thermally conductive coating significantly improves the overall performance of the ultra-thin honeycomb aluminum coating. The thermal conductivity design of the insulating and intermediate layers balances electrical safety and heat dissipation requirements, extending the lifespan of the surface layer.

[0029] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A highly flexible circuit board, comprising copper foil (1), adhesive layer one (2), aluminum honeycomb core (3), adhesive layer two (4), and PI layer (5), characterized in that: The upper and lower sides of the copper foil (1) are fixedly connected to the aluminum honeycomb core (3) by adhesive layer one (2), the top of the aluminum honeycomb core (3) at the top is fixedly connected to the PI layer (5) by adhesive layer two (4), and the bottom of the aluminum honeycomb core (3) at the bottom is fixedly connected to the PI layer (5) by adhesive layer two (4).

2. The highly flexible circuit board according to claim 1, characterized in that: The thickness of the aluminum honeycomb core (3) is 0.05 mm, and the honeycomb pore size of the aluminum honeycomb core (3) is 0.05 mm.

3. The highly flexible circuit board according to claim 1, characterized in that: The honeycomb orientation of the aluminum honeycomb core (3) is consistent with the bending direction of the flexible circuit board.

4. The highly flexible circuit board according to claim 1, characterized in that: The surface of the aluminum honeycomb core (3) is coated with a composite insulating and thermally conductive coating, which includes an insulating layer, an intermediate layer and a surface layer.

5. A highly flexible circuit board according to claim 4, characterized in that: The insulating layer uses a polyimide solution and has a thickness of 5-8 μm.

6. A highly flexible circuit board according to claim 4, characterized in that: The intermediate layer uses epoxy resin mixed with silicon carbide nanoparticles, with a thickness of 2-3 μm.

7. A highly flexible circuit board according to claim 4, characterized in that: The surface layer uses fluorinated organosilicon with a thickness of 0.5-1 μm.

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