Flexible circuit board without ACF hot pressing

Abstract

The invention discloses a flexible circuit board without ACF hot pressing. An upper silver wire is printed on the surface of an upper PET layer and is correspondingly printed with upper PAD points and upper silver points; the lower-layer silver wire is printed on the surface of the lower-layer PET and is correspondingly printed with a lower-layer PAD point and a lower-layer silver point; the surface of the lower layer PET is provided with punched holes, the punched holes correspond to the through holes in the surface of the middle layer PET, and the punched holes and the through holes are filled with electric conductors, so that the upper layer silver points are connected with the lower layer silver points through the electric conductors. According to the invention, an appropriate position can be selected as required to print the upper-layer silver point and the lower-layer silver point, so that the decentralized design is realized, the required space is small, the wiring difficulty is reduced, the length of the silver wire is shortened, and the cost is reduced; moreover, the manufacturing process of the structure can replace an ACF hot pressing process, so that three work stations including conductive adhesive pasting, conductive adhesive detecting and hot pressing are omitted, the equipment cost is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit board technology, and in particular to a flexible circuit board without ACF hot pressing. Background Technology

[0002] Flexible printed circuit boards (FPCBs) are mainly used in home appliance buttons, computer buttons, and various button-function devices. They achieve their electrical functions by printing conductive silver paste, insulating UV coatings, carbon fiber, and waterproof adhesive onto PET substrates.

[0003] like Figure 1-4 Currently, the conventionally designed flexible circuit board includes, in sequence, an upper PET layer 1, an upper silver wire 2, an upper waterproof adhesive 3, a middle PET layer 4, a lower waterproof adhesive 5, a conductive adhesive 6, a lower silver wire 7, and a lower PET layer 8. The upper silver wire 2 is printed on the surface of the upper PET layer and has corresponding upper PAD points 11 and upper hot-pressed silver points 12. The upper waterproof adhesive 3 is applied to the surface of the upper PET layer and exposes the upper PAD points 11 and upper hot-pressed silver points 12. The lower silver wire 7 is printed on the surface of the lower PET layer 8 and has corresponding lower PAD points 9 and lower hot-pressed silver points 10. The lower waterproof adhesive 5 is applied to the surface of the lower PET layer 8 and exposes the lower PAD points 9 and lower hot-pressed silver points 10. Conductive adhesive 6 is applied between the upper hot-pressed silver points 12 and the lower hot-pressed silver points 10. The upper and lower layers are combined with the middle PET layer 4 and then formed into a flexible circuit board through an ACF hot-pressing process.

[0004] The aforementioned prior art involves designing hot-pressed silver dots on two layers of PET, attaching conductive adhesive 6 between the two layers of hot-pressed silver dots, connecting the upper layer silver wire 2 to the corresponding upper layer PAD point 11, and then connecting it to the upper layer hot-pressed silver point 12. A portion of the lower layer silver wire 7 is connected to the corresponding lower layer PAD point 9, and another portion of the lower layer silver wire 7 is connected to the lower layer hot-pressed silver point 10. The upper layer hot-pressed silver point 12 corresponds to the lower layer hot-pressed silver point 10. Through the ACF hot-pressing process, the hot-pressed silver dots of the upper and lower layers are connected together, ultimately achieving electrical functionality.

[0005] However, the existing flexible circuit boards with the above-mentioned structure and conventional ACF hot pressing process require the design of hot-pressed silver points. In order to facilitate ACF hot pressing, the hot-pressed silver points need to be designed together, which requires a large space and increases the difficulty of wiring. In addition, three separate workstations are required for applying conductive adhesive, inspecting conductive adhesive, and hot pressing, resulting in high equipment investment costs and a large footprint, ultimately leading to high production costs and low production efficiency. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a flexible circuit board without ACF hot pressing, comprising an upper PET layer, an upper silver wire layer, an upper waterproof adhesive layer, a middle PET layer, a lower waterproof adhesive layer, a lower silver wire layer, and a lower PET layer arranged sequentially. The upper silver line is printed on the surface of the upper PET layer and corresponding upper PAD dots and upper silver dots are printed. The upper waterproof adhesive is applied to the surface of the upper PET layer and exposes the upper PAD dots and upper silver dots. The lower layer silver line is printed on the surface of the lower layer PET and correspondingly printed with lower layer PAD dots and lower layer silver dots. The lower layer waterproof adhesive is applied to the surface of the lower layer PET and exposes the lower layer PAD dots and lower layer silver dots. The surface of the lower PET layer is provided with perforations, which correspond to the through holes on the surface of the middle PET layer. Conductors are filled in the perforations and through holes so that the upper silver dots and the lower silver dots are connected through the conductors.

[0007] The diameter of the punch hole is smaller than the diameter of the through hole.

[0008] Wherein, a protective layer is provided on the surface of the conductor, and the protective layer is used to protect the conductor.

[0009] Through the above technical solution, the present invention can select appropriate positions for printing upper and lower silver dots as needed, which means that the design can be distributed, requiring less space, reducing the difficulty of wiring, shortening the length of silver lines, and thus reducing costs. Moreover, the manufacturing process of this structure can replace the ACF hot pressing process, thereby eliminating three workstations such as applying conductive adhesive, checking conductive adhesive, and hot pressing, reducing equipment costs and improving production efficiency. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0011] Figure 1 A schematic diagram of the exploded structure of a flexible circuit board in the prior art; Figure 2 A schematic diagram of the structure for printing upper-layer silver lines on upper-layer PET in existing technology; Figure 3 A schematic diagram of the structure for printing a lower layer of silver lines on a lower layer of PET in the prior art; Figure 4 This is a partial cross-sectional view of the assembled flexible circuit board structure in the prior art. Figure 5 This is an exploded view of the flexible circuit board structure of the present invention; Figure 6 This is a schematic diagram of the structure of printing upper silver lines on the upper PET layer of the present invention; Figure 7 This is a schematic diagram of the structure of printing a lower layer of silver lines on the lower PET layer of the present invention; Figure 8This is a partial cross-sectional view of the flexible circuit board assembly structure of the present invention.

[0012] The numbers in the diagram represent: 1. Upper PET layer; 2. Upper silver wire layer; 3. Upper waterproof adhesive layer; 4. Middle PET layer; 5. Lower waterproof adhesive layer; 6. Conductive adhesive layer; 7. Lower silver wire layer; 8. Lower PET layer; 9. Lower PAD point layer; 10. Lower hot-pressed silver point layer; 11. Upper PAD point layer; 12. Upper hot-pressed silver point layer; 13. Lower silver point layer; 14. Upper silver point layer; 15. Conductor layer; 16. Protective layer. Detailed Implementation

[0013] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0014] refer to Figure 5-8 The flexible circuit board disclosed in this embodiment is a non-ACF hot-pressing type, which includes an upper PET1, an upper silver wire 2, an upper waterproof adhesive 3, a middle PET4, a lower waterproof adhesive 5, a lower silver wire 7 and a lower PET8 arranged in sequence. The upper silver line 2 is printed on the surface of the upper PET1 and the upper PAD dot 11 and upper silver dot 14 are printed accordingly. The upper waterproof adhesive 3 is applied to the surface of the upper PET1 and the upper PAD dot 11 and upper silver dot 14 are exposed. The lower silver line 7 is printed on the surface of the lower PET8 and the lower PAD dot 9 and lower silver dot 13 are printed accordingly. The lower waterproof adhesive 5 is applied to the surface of the lower PET8 and exposes the lower PAD dot 9 and lower silver dot 13. The surface of the lower PET8 is provided with perforations, which correspond to the through holes on the surface of the middle PET4. Conductors 15 are filled in the perforations and through holes so that the upper silver dots 14 and the lower silver dots 13 are connected through the conductors 15. A protective layer 16 is provided on the surface of the conductors 15 to protect the conductors 15.

[0015] Among them, such as Figure 8 As shown, the diameter of the punch is smaller than the diameter of the through hole. After the lower PET8 is punched, the conductor 15 needs to connect the silver phase on the surface and side of the upper silver point 14 and the lower silver point 13. If the diameter of the through hole on the surface of the middle PET4 is less than or equal to the diameter of the punch of the lower PET8, it will cover the silver on the surface of the lower silver point 13, and only the silver on the side will be connected, resulting in a smaller connection area and affecting the conductivity.

[0016] The present invention allows for the printing of upper silver dots 14 and lower silver dots 13 at appropriate locations as needed, enabling distributed design, requiring less space, reducing wiring difficulty, shortening silver line length, and thus reducing costs. Moreover, the manufacturing process of this structure can replace the ACF hot pressing process, thereby eliminating three workstations: applying conductive adhesive, inspecting conductive adhesive, and hot pressing, reducing equipment costs and improving production efficiency.

[0017] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to the above embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A flexible circuit board without ACF hot pressing, comprising an upper PET layer (1), an upper silver wire layer (2), an upper waterproof adhesive layer (3), a middle PET layer (4), a lower waterproof adhesive layer (5), a lower silver wire layer (7), and a lower PET layer (8) arranged sequentially, characterized in that: The upper silver line (2) is printed on the surface of the upper PET (1) and the upper PAD point (11) and upper silver point (14) are printed accordingly. The upper waterproof adhesive (3) is attached to the surface of the upper PET (1) and exposes the upper PAD point (11) and upper silver point (14). The lower silver line (7) is printed on the surface of the lower PET (8) and the lower PAD point (9) and lower silver point (13) are printed accordingly. The lower waterproof adhesive (5) is attached to the surface of the lower PET (8) and exposes the lower PAD point (9) and lower silver point (13). The surface of the lower PET (8) is provided with perforations, which correspond to the through holes on the surface of the middle PET (4). Conductors (15) are filled in the perforations and through holes, so that the upper silver dots (14) and the lower silver dots (13) are connected through the conductors (15).

2. The flexible circuit board without ACF hot pressing according to claim 1, characterized in that, The diameter of the punch hole is smaller than the diameter of the through hole.

3. The flexible circuit board without ACF hot pressing according to claim 1 or 2, characterized in that, A protective layer (16) is provided on the surface of the conductor (15), the protective layer (16) being used to protect the conductor (15).

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