Flexible printed circuit (FPC)

Abstract

The utility model relates to the field of keyboard circuit boards, in particular to a flexible printed circuit (FPC), which comprises a flexible board body, the flexible board body comprises a main board, two connecting films connected with the upper side and the lower side of the main board and at least one hole penetrating through the main board and the connecting films, and a conductive silver paste layer is arranged in the hole. By directly forming the hole in the main board and filling the conductive silver paste layer, the subsequent processing steps are reduced, the overall integration level of the FPC soft board is improved, the step of plugging the hole in the PI / PET film through a vacuum hole plugging machine in the prior art is omitted, the production efficiency of the FPC soft board is improved, meanwhile, the phenomenon of hole plugging missing is avoided, and the qualified rate of products is effectively improved; the connecting films are added to the upper side and the lower side of the main board, so that the conductive silver paste on the surface of the FPC can be effectively prevented from being short-circuited, and meanwhile, the main board is protected from external damage during processing.

Description

Technical Field

[0001] The utility model relates to the field of keyboard circuit boards, in particular to an FPC soft board. Background Art

[0002] As an indispensable input device of a computer, a keyboard is usually composed of multiple keys, each of which must be connected to a circuit board. The circuit board of the keyboard is mainly an FPC soft board. People achieve the purpose of control by silk-screening the circuit on the FPC soft board. However, since the existing FPC soft boards are all post-processed, the PI / PET film is plugged by a vacuum plugging machine for filling with conductive silver paste, and then the plugging is performed point-to-point. Therefore, it is easy to cause leaking plugging when the vacuum plugging machine is used for plugging, and it is easy to cause short circuit when the plugging surface is printed point-to-point. At the same time, the production process is complicated, resulting in a high production cost of the FPC soft board. Therefore, it is necessary to develop an FPC soft board to improve the phenomenon of leaking plugging and short circuit in the existing process, and at the same time optimize the production process of the FPC soft board, improve production efficiency and reduce production costs, and improve product quality. Utility Model Content

[0003] In view of the above-mentioned prior art process of plugging holes in PI / PET film by vacuum plugging machine for filling conductive silver paste, which is prone to leaking and short circuit, as well as complicated production process, the technical solution adopted by the utility model to solve the technical problem is:

[0004] An FPC soft board includes a soft board body, wherein the soft board body includes a main board, two connecting films connected to the upper side and the lower side of the main board, and at least one hole penetrating the main board and the connecting film, wherein a conductive silver paste layer is arranged in the hole.

[0005] A FPC soft board, wherein a side of the connecting film connected to the main board is coated with a slight adhesive.

[0006] An FPC soft board, wherein the thickness of the connecting film ranges from 10 μm to 50 μm, and the connecting film is a PI or PET film.

[0007] An FPC soft board, wherein the diameter of the hole is less than or equal to the width of the main board, and the diameter range of the hole is 0.5mm-2.5mm.

[0008] A FPC soft board, wherein the main board is a PI film and the connecting film is a PI film.

[0009] A FPC soft board, wherein the main board is a PET film and the connecting film is a PET film.

[0010] An FPC soft board, the thickness of the main board ranges from 0.02mm to 1.4mm, and the main board is a PI or PET film.

[0011] An FPC flexible board, the flexible board body further includes a plurality of circuit grooves penetrating the connection film.

[0012] An FPC flexible board, on the surface of the main board are provided circuit grooves, and a plurality of the circuit grooves are connected to the conductive silver paste layer.

[0013] An FPC flexible board, the connection film and the main board are detachably connected.

[0014] The beneficial effects of the present utility model are as follows:

[0015] By directly forming holes on the main board and filling with a conductive silver paste layer, the present utility model reduces subsequent processing steps, improves the overall integration of the FPC flexible board, cancels the step of plugging holes in the PI / PET film by the original vacuum hole plugging machine, improves the production efficiency of the FPC flexible board, and at the same time avoids the phenomenon of missed hole plugging, effectively improving the qualified rate of the product. Secondly, by adding connection films on the upper and lower sides of the main board, it can effectively prevent the conductive silver paste on the surface of the FPC flexible board from short-circuiting, and at the same time play a role in protecting the main board from external damage during processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of an FPC flexible board of the present utility model.

[0017] Figure 2 is an exploded view of an FPC flexible board of the present utility model.

[0018] Figure 3 is an exploded view of an FPC flexible board of the present utility model.

[0019] Figure 4 is an exploded view of an FPC flexible board of the present utility model.

[0020] Figure 5 is an exploded view of an FPC flexible board of the present utility model.

[0021] Figure 6 is a schematic structural diagram of an FPC flexible board of the prior art. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following will describe in detail the embodiments of the present utility model with reference to the accompanying drawings.

[0023] Please refer to Figures 1 to 6, an FPC flexible printed circuit board, comprising a flexible board body 1. The flexible board body 1 includes a main board 11, two connecting films 12 connected to the upper and lower sides of the main board 11, and at least one hole 13 penetrating through the main board 11 and the connecting film 12. A conductive silver paste layer 131 is provided in the hole 13. The main board 11 is used to carry circuits and has good flexibility, enabling the FPC flexible printed circuit board to work stably in various bending and folding application scenarios. At the same time, by directly forming the hole 13 in the main board 11 and filling it with the conductive silver paste layer 131, subsequent processing steps are reduced, the overall integration of the FPC flexible printed circuit board is improved, the step of plugging holes in the PI / PET film by a vacuum hole plugging machine in the prior art is cancelled, the production efficiency of the FPC flexible printed circuit board is increased, and the phenomenon of missed hole plugging is avoided, effectively improving the qualified rate of the product. Further, the hole 13 enables the FPC flexible printed circuit board to establish electrical connections between different layers without connecting through external circuits or connectors, which not only simplifies the circuit layout but also reduces the overall volume and weight. The connection films 12 provided on the upper and lower sides of the main board 11 can effectively prevent the conductive silver paste on the surface of the FPC flexible printed circuit board from short-circuiting, and at the same time play a role in protecting the main board from external damage during processing. When baked at high temperature, the conductive silver paste melts and fills into the hole 13, and the connecting film 12 can be torn off after cooling to remove the excess conductive silver paste remaining on the connecting film 12.

[0024] Further, please refer to Figures 1 to 6 , an FPC flexible printed circuit board, and a micro adhesive is coated on the side of the connecting film 12 connected to the main board 11. With such a design, it means that the connection between the connecting film 12 and the main board 11 is achieved through the micro adhesive. The function of the micro adhesive is to provide sufficient adhesion to maintain the stable combination of the connecting film 12 and the main board 11, so as to prevent the connecting film 12 from separating from the main board 11 during high-temperature baking and perfusion of the conductive silver paste, which may otherwise lead to ineffective protection of the main board 11 from isolating the conductive silver paste. At the same time, it is not too viscous to be difficult to disassemble, thus facilitating the tearing of the connecting film 12 during the subsequent use of the FPC flexible printed circuit board. Such a design can not only enable the connecting film 12 to effectively protect the main board 11 but also simplify the production process and reduce the production cost of the FPC flexible printed circuit board.

[0025] Further, please refer to Figures 1 to 6, a flexible printed circuit (FPC) board. The thickness range of the connecting film 12 is 10μm - 50μm, and the connecting film 12 is a PI or PET film. The thickness of the connecting film 12 directly affects the flexibility of the FPC board. A thinner connecting film 12 makes the FPC board more flexible, easier to bend and fold. At the same time, the overall thickness of the FPC board is also thinner, enabling it to be applied to products with limited space, such as wearable devices, flexible displays, and laptop keyboards. A thicker connecting film 12 provides certain structural support, allowing the FPC board to resist a certain degree of mechanical stress while maintaining a certain level of flexibility. Further, an appropriate thickness of the connecting film 12 helps improve the reliability of the FPC board. An overly thin connecting film 12 may be more vulnerable to the external environment, resulting in a decrease in adhesion or damage. An appropriate thickness can provide better protection for the main board 11. In summary, it is most reasonable to set the thickness range of the connecting film 12 between 10μm - 50μm. In practical applications, selecting and adjusting the thickness of the connecting film 12 according to requirements can meet the demands for flexibility, electrical performance, production cost, and reliability of the FPC board in different application scenarios, effectively improving the practicality of the FPC board. Further, the PI film is a high-performance insulating material with good heat resistance, chemical corrosion resistance, and mechanical strength. The PET film also has good mechanical strength and electrical insulation properties. Further, both PI and PET are materials with good flexibility, enabling the FPC board to maintain stable insulation performance under various bending, folding, and twisting conditions. Specifically, the PI film can withstand a high temperature of up to 400 degrees Celsius in a short period, while the PET film can withstand a temperature of 200 - 300 degrees Celsius in a short period. The melting point of commonly used conductive silver paste is usually between 100 - 200 degrees Celsius, and both the PI film and the PET film can withstand the temperature during high-temperature baking for pouring conductive silver paste. Therefore, the PI film and the PET film can meet the requirements of the connecting film 12.

[0026] Further, please refer to Figures 1 to 6, an FPC flexible board, the diameter of the hole 13 is less than or equal to the width of the main board 11, and the diameter range of the hole 13 is 0.5mm - 2.5mm. The hole 13 serves as a connection channel between circuits on different layers in the main board 11, and its diameter determines the filling amount and conductivity of the conductive silver paste layer 131. The hole 13 with a diameter range between 0.5mm - 2.5mm can not only ensure sufficient conductive area but also avoid waste of conductive silver paste due to overly large holes. At the same time, the diameter of the hole 13 also affects the mechanical strength of the FPC flexible board. An overly small hole 13 may increase processing difficulty and may cause breakage or deformation of the hole 13; while an overly large hole 13 may weaken the overall structural strength of the FPC flexible board. Therefore, preferably, the diameter range of the hole 13 is controlled within 0.5mm - 2.5mm, and the diameter of the hole 13 is adjusted according to different application scenarios.

[0027] Furthermore, during the production process, the diameters of the holes 13 in the FPC flexible boards of the same batch are consistent to avoid problems such as electrical connection issues or uneven mechanical strength caused by aperture differences.

[0028] Furthermore, please refer to Figures 1 to 6 , an FPC flexible board, the main board 11 is a PI film, and the connecting film 12 is a PI film. The PI film is a high-performance insulating material with good heat resistance, chemical corrosion resistance, and mechanical strength. Furthermore, PI is a material with good flexibility, enabling the FPC flexible board to maintain stable insulating performance under various bending, folding, and twisting conditions. And the materials of both the connecting film 12 and the main board 11 being PI films can reduce the material differences of various components of the FPC flexible board and effectively improve the integrity of the FPC flexible board.

[0029] Furthermore, please refer to Figures 1 to 6 , an FPC flexible board, the main board 11 is a PET film, and the connecting film 12 is a PET film. The PET film also has good heat resistance, chemical corrosion resistance, and mechanical strength. Furthermore, PET is a material with good flexibility, enabling the FPC flexible board to maintain stable insulating performance under various bending, folding, and twisting conditions. And the materials of both the connecting film 12 and the main board 11 being PET films can reduce the material differences of various components of the FPC flexible board and effectively improve the integrity of the FPC flexible board.

[0030] Furthermore, please refer to Figures 1 to 6, an FPC flexible board, the thickness range of the main board 11 is 0.02mm - 1.4mm, and the main board 11 is a PI or PET film. The main board 11 is used to carry circuits. Preferably, the thickness range of the main board 11 is controlled within 0.02mm - 1.4mm because the thickness of the main board 11 will directly affect the flexibility of the FPC flexible board. A thinner main board 11 makes the FPC flexible board have extremely high flexibility and can easily handle various bends and folds, being very suitable for application scenarios that require high flexibility, such as wearable devices, flexible displays, and laptop keyboards, etc. While a thicker main board 11 provides stronger structural support and is suitable for occasions that require a certain degree of rigidity and stability. However, an overly thin main board 11 will cause the FPC flexible board to be more easily damaged due to insufficient structural strength, and at the same time, higher technical requirements and more precise equipment are needed in production, thus increasing production costs; an overly thick main board 11 will cause the FPC flexible board to lose its flexibility and cannot be effectively applied to some irregular products. Therefore, setting the main board 11 between 0.02mm - 1.4mm is a reasonable range that can meet the requirements for the flexibility, electrical performance, production cost, and reliability of the FPC flexible board in different application scenarios. In actual applications, it is necessary to make selections and adjustments according to specific requirements. Further, both PI and PET are materials with good flexibility, enabling the FPC flexible board to maintain stable insulation performance under various bending, folding, and twisting conditions. Specifically, the PI film can withstand a high temperature of up to 400 degrees Celsius in a short period, while the PET film can withstand a temperature of 200 - 300 degrees Celsius in a short period. The melting point of commonly used conductive silver paste is usually between 100 - 200 degrees Celsius, and both the PI film and the PET film can withstand the temperature during high-temperature baking and perfusion of conductive silver paste. Therefore, the PI film and the PET film can meet the requirements of the main board 11.

[0031] Further, please refer to Figures 1 to 6 , an FPC flexible board, the flexible board body 1 further includes a plurality of circuit grooves 14 penetrating through the connection film 12. The circuit grooves 14 provide channels for the printed circuit of the FPC flexible board. When conducting circuit printing, the conductive silver paste melts under high-temperature baking and fills into the circuit grooves. After cooling, a circuit is formed. After the circuit is formed, the connection film 12 can be torn off to remove the excess conductive silver paste, effectively avoiding the situation of short circuits caused by the remaining excess conductive silver paste on the FPC flexible board, improving the production qualification rate of the FPC flexible board. Further, by adjusting the position and shape of the circuit grooves 14, the layout and optimization of the circuit can be realized, improving the circuit integration and performance, and effectively improving the production efficiency of the FPC flexible board.

[0032] Further, please refer to Figures 1 to 6, an FPC flexible board, wherein the surface of the main board 11 is provided with the circuit grooves 14, and a plurality of the circuit grooves 14 are connected to the conductive silver paste layer 131. Through the connection between the circuit grooves 14 and the conductive silver paste layer 131, after pouring the conductive silver paste into the circuit grooves 14 during circuit printing, the electrical connection between the internal circuits of the FPC flexible board is realized. By adopting this method, the circuit is tightly connected to the conductive silver paste layer 131, enhancing the stability between the circuit and the main board 11, effectively enhancing the reliability of the electrical connection of the FPC flexible board. This connection method can help prevent electrical faults such as poor contact, open circuit or short circuit, and effectively improve the overall performance and stability of the FPC flexible board.

[0033] Further, please refer to Figures 1 to 6 , an FPC flexible board, wherein the connection film 12 is detachably connected to the main board 11. The function of the connection film 12 in the present utility model is to protect the main board 11 during the production process and prevent the excess conductive silver paste from causing a short circuit of the FPC flexible board after the conductive silver paste perfusion is completed. Specifically, after the conductive silver paste melted by high-temperature baking fills into the circuit grooves 14, the excess conductive silver paste remains on the surface of the connection film 12. The detachable connection design between the connection film 12 and the main board 11 enables the excess conductive silver paste remaining on the connection film 12 to be removed together when tearing off the connection film 12, so as to prevent the excess conductive silver paste from causing a short circuit of the FPC flexible board, effectively improving the production qualification rate of the FPC flexible board.

[0034] Embodiment 1

[0035] As Figure 1 , Figure 2 shown, an FPC flexible board includes a flexible board body 1, and the flexible board body 1 includes a main board 11, two connection films 12 connected to the upper side and the lower side of the main board 11, and at least one hole 13 penetrating through the main board 11 and the connection film 12. A conductive silver paste layer is provided in the hole 13.

[0036] Further, one side of the connection film 12 connected to the main board 11 is coated with a micro adhesive.

[0037] Further, the thickness of the connection film 12 is 10 μm.

[0038] Further, the diameter of the hole 13 is less than or equal to the width of the main board 11, and the diameter of the hole 13 is 0.5 mm.

[0039] Further, the main board 11 is a PI film, and the connection film 12 is a PI film.

[0040] Further, the thickness of the main board 11 is 0.02 mm.

[0041] Further, the connection film 12 and the main board 11 are detachably connected.

[0042] In this embodiment, during the process of filling the conductive silver paste of the FPC flexible board, the conductive silver paste is filled into the holes 13 after high-temperature baking. After cooling, a semi-finished product of the FPC flexible board without printed circuits is obtained.

[0043] Embodiment 2

[0044] As Figure 3 shown, an FPC flexible board includes a flexible board body 1. The flexible board body 1 includes a main board 11, two connection films 12 connected to the upper and lower sides of the main board 11, and at least one hole 13 penetrating through the main board 11 and the connection film 12. A conductive silver paste layer is provided in the hole 13.

[0045] Further, a micro adhesive is coated on the side of the connection film 12 connected to the main board 11.

[0046] Further, the thickness of the connection film 12 is 50 μm.

[0047] Further, the diameter of the hole 13 is less than or equal to the width of the main board 11, and the diameter of the hole 13 is 2.5 mm.

[0048] Further, the main board 11 is a PET film, and the connection film 12 is a PET film.

[0049] Further, the thickness of the main board 11 is 1.4 mm.

[0050] Further, the flexible board body 1 further includes a plurality of circuit grooves 14 penetrating through the connection film 12.

[0051] Further, the connection film 12 and the main board 11 are detachably connected.

[0052] In this embodiment, during the process of filling the conductive silver paste of the FPC flexible board, the conductive silver paste is filled into the holes 13 and the circuit grooves 14 after high-temperature baking, and a complete circuit is formed on the FPC flexible board. Then, the connection film 12 is torn off to remove the excess conductive silver paste, and finally, the finished product of the FPC flexible board is obtained.

[0053] Embodiment 3

[0054] As Figure 4 shown, an FPC flexible board includes a flexible board body 1. The flexible board body 1 includes a main board 11, two connection films 12 connected to the upper and lower sides of the main board 11, and at least one hole 13 penetrating through the main board 11 and the connection film 12. A conductive silver paste layer is provided in the hole 13.

[0055] Further, one side of the connecting film 12 connected to the main board 11 is coated with a micro adhesive.

[0056] Further, the thickness of the connecting film 12 is 25 μm.

[0057] Further, the diameter of the hole 13 is less than or equal to the width of the main board 11, and the diameter of the hole 13 is 1.5 mm.

[0058] Further, the main board 11 is a PI film, and the connecting film 12 is a PET film.

[0059] Further, the thickness of the main board 11 is 0.8 mm.

[0060] Further, the circuit grooves 14 are provided on the surface of the main board 11, and multiple circuit grooves 14 are connected to the conductive silver paste layer 131.

[0061] Further, the connecting film 12 and the main board 11 are detachably connected.

[0062] In this embodiment, during the process of filling the FPC flexible board with conductive silver paste, the conductive silver paste is filled into the hole 13 and the circuit groove 14 after high-temperature baking to form a complete circuit on the FPC flexible board, and then the connecting film 12 is torn off to remove the excess conductive silver paste, and finally the finished product of the FPC flexible board is obtained.

[0063] Embodiment 4

[0064] As Figure 4 shown, an FPC flexible board includes a flexible board body 1, and the flexible board body 1 includes a main board 11, two connecting films 12 connected to the upper side and the lower side of the main board 11, and at least one hole 13 penetrating through the main board 11 and the connecting film 12, and a conductive silver paste layer is provided in the hole 13.

[0065] Further, one side of the connecting film 12 connected to the main board 11 is coated with a micro adhesive.

[0066] Further, the thickness of the connecting film 12 is 15 μm.

[0067] Further, the diameter of the hole 13 is less than or equal to the width of the main board 11, and the diameter of the hole 13 is 1 mm.

[0068] Further, the main board 11 is a PET film, and the connecting film 12 is a PI film.

[0069] Further, the thickness of the main board 11 is 0.2 mm.

[0070] Further, a circuit groove 14 is provided on the surface of the main board 11, and a plurality of the circuit grooves 14 are connected to the conductive silver paste layer 131.

[0071] Further, the connection film 12 is detachably connected to the main board 11.

[0072] In this embodiment, during the process of filling the FPC flexible board with conductive silver paste, the conductive silver paste is filled into the holes 13 and the circuit grooves 14 after high-temperature baking to form a complete circuit on the FPC flexible board, and then the connection film 12 is torn off to remove the excess conductive silver paste, and finally the finished FPC flexible board is obtained.

[0073] Embodiment 5

[0074] As Figure 5 shown, the connection film 12 of the semi-finished FPC flexible board in Embodiment 1 is torn off, and then the circuit is printed to obtain the finished FPC flexible board.

[0075] The above only further illustrates the technical content of the present invention with embodiments to make it easier for readers to understand, but it does not mean that the implementation manners of the present invention are limited to this. Any technical extension or re-creation made according to the present invention is protected by the present invention. The protection scope of the present invention is subject to the claims.

Claims

1. An FPC soft board, comprising a soft board body (1), characterized in that: The flexible board body (1) comprises a main board (11), two connection films (12) connected to the upper side and the lower side of the main board (11), and at least one hole (13) penetrating the main board (11) and the connection film (12), wherein a conductive silver paste layer (131) is provided in the hole (13).

2. The FPC according to claim 1, characterized in that: A micro-adhesive is coated on one side of the connection film (12) connected to the main board (11).

3. The FPC according to claim 1, characterized in that: The thickness of the connecting film (12) is in the range of 10 μm to 50 μm, and the connecting film (12) is a PI or PET film.

4. The FPC according to claim 1, characterized in that: The diameter of the hole (13) is less than or equal to the width of the main board (11), and the diameter range of the hole (13) is 0.5 mm-2.5 mm.

5. The FPC according to claim 1, characterized in that: The main board (11) is a PI film, and the connecting film (12) is a PI film.

6. The FPC according to claim 1, characterized in that: The main board (11) is a PET film, and the connecting film (12) is a PET film.

7. The FPC according to claim 1, characterized in that: The thickness of the main board (11) ranges from 0.02 mm to 1.4 mm, and the main board (11) is a PI or PET film.

8. The FPC according to claim 1, characterized in that: The flexible board body (1) further comprises a plurality of circuit grooves (14) penetrating the connection film (12).

9. The FPC according to claim 1, characterized in that: A circuit groove (14) is provided on the surface of the mainboard (11), and a plurality of the circuit grooves (14) are connected to the conductive silver paste layer (131).

10. The FPC according to claim 1, characterized in that: The connecting film (12) is detachably connected to the main board (11).

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