A modular flexible circuit board capable of being quickly assembled

Abstract

The application relates to the technical field of flexible circuit manufacturing, and provides a modular flexible circuit board capable of being quickly spliced, which comprises at least two flexible circuit units arranged in sequence and independently arranged; the end of each flexible circuit unit is fixedly connected with a connecting shell, the connecting shell is provided with a magnetic positioning structure and a UV glue bonding fixing structure for quick splicing; each flexible circuit unit comprises an internal conductive circuit and an insulating isolation layer wrapped on the outer surface of the conductive circuit; one end of each flexible circuit unit is provided with an external connecting terminal for connecting with external electronic components; the other end of the flexible circuit unit corresponds to the connecting shell and forms a splicing interface for splicing with an adjacent flexible circuit unit; each flexible circuit unit can be taken out independently and used as a complete independent flexible circuit board, so that small-scale or single-wiring distribution requirements can be met.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit manufacturing technology, and in particular to a modular flexible circuit board that can be quickly assembled. Background Technology

[0002] Flexible printed circuit boards (FPCBs) are printed circuit boards made with polyimide or other flexible insulating materials as the substrate, possessing high reliability and excellent flexibility. FPCBs are lightweight, small in size, foldable, bendable, and rollable, allowing for three-dimensional arrangement to achieve thinner and lighter designs. This facilitates circuit board installation and product assembly, offering strong installation adaptability and eliminating the need for some connectors. It significantly reduces the size and weight of electronic products, meeting the needs of electronic products moving towards higher density, miniaturization, and higher reliability.

[0003] Existing spliced ​​flexible circuit boards can usually only be used as a whole, and individual circuit units cannot be taken out and used independently. They lack the dual-mode switching capability of "single module working independently" and "multi-module working collaboratively", which limits their flexibility and adaptability in different application scenarios.

[0004] A prominent structural contradiction exists in existing splicing solutions: some solutions directly embed magnets and limiting structures onto the FPC thin sheet body. However, the FPC substrate is extremely thin, and machining mounting holes, embedding magnets, or forming protrusion structures on it is not only extremely difficult and costly, but also creates localized rigid areas in the embedded rigid components. During repeated bending, stress concentration easily occurs at the interface between the FPC substrate and the rigid components in these areas, leading to breakage of conductive lines. This contradiction has not been effectively resolved in existing technologies.

[0005] Existing patents, such as Guangzhou Qingchang Electronics Co., Ltd.'s "A Splicable Flexible Circuit Board" (Chinese Patent Announcement No. CN221979199U), employ a method of sliding splicing of limiting grooves and limiting blocks, reinforced by magnetic attraction between the N and S poles of magnets. However, this method still has the following shortcomings: First, in this solution, magnetic attraction is only used as an auxiliary reinforcement method and lacks an active guiding and positioning function; second, this solution lacks a permanent fixing method, and there is a risk of loosening under vibration; third, this solution directly sets the magnets and limiting structures on the FPC thin plate, which is difficult to process and poses a risk of stress concentration; fourth, each splicing unit cannot be independently removed and used separately.

[0006] For example, Foshan Guoli Optoelectronics Technology Co., Ltd.'s "A Splicable Flexible Circuit Board" (Chinese Patent Authorization Announcement No. CN222321829U) uses a combination of connecting shell one and connecting shell two with a card slot and docking groove. However, its structure is complex, has a large number of parts, and has high manufacturing costs. Moreover, it uses a purely mechanical connection method, which causes wear problems after repeated disassembly and assembly. It also does not have the function of using a single circuit unit independently.

[0007] Therefore, there is an urgent need in this field for a modular flexible circuit board that can achieve rapid splicing, ensure connection reliability, avoid stress concentration, maintain the flexibility of the splicing joint, and enable independent use of a single module. Summary of the Invention

[0008] In view of this, the purpose of one or more embodiments of this specification is to propose a modular flexible circuit board that can be quickly spliced, solving the problems of traditional flexible circuit boards that cannot be replaced individually and have poor docking accuracy. At the same time, by setting the interface structure on the connecting shell and setting a flexible reinforcing film on the back of the splice, the problem of stress concentration and easy damage in the splicing area is solved, realizing a dual-mode application in which each flexible circuit unit can be taken out and used independently, or can be spliced ​​together to form a circuit of any length.

[0009] For the purposes described above, one or more embodiments of this specification provide a modular flexible circuit board that can be quickly assembled, including at least two sequentially arranged and independently configured flexible circuit units.

[0010] Each of the flexible circuit units is fixedly connected to a connecting shell at its end. The connecting shell is provided with a magnetic positioning structure and a UV adhesive bonding and fixing structure for quick assembly. Each of the flexible circuit units includes internal conductive lines and an insulating layer wrapped around the outer surface of the conductive lines; Each of the flexible circuit units has an external terminal block at one end for connecting to external electronic components, and the other end of the flexible circuit unit forms a splicing interface for splicing with adjacent flexible circuit units at the connection shell. The flexible circuit units are sequentially spliced ​​together by the connecting shell to form a chain circuit board as a whole. Each of the flexible circuit units can be used as a complete flexible circuit board in an independent state. The back of the connecting shell is also provided with a flexible reinforcing membrane. The flexible reinforcing membrane spans the splicing point of two adjacent connecting shells and is used to transfer and disperse stress from the splicing point to the flexible reinforcing membrane when the circuit board is bent as a whole after splicing.

[0011] Furthermore, the magnetic positioning structure is a magnetic splicing hole provided at the corner end of the connecting shell. The magnetic splicing hole is provided with a magnetic adsorption element, which is used to automatically adsorb, align and position the adjacent connecting shells by magnetic force during splicing. The magnetic adsorption element includes an N-pole magnet and an S-pole magnet, which are arranged in pairs at corresponding corner positions of adjacent connecting shells.

[0012] Furthermore, the UV adhesive bonding and fixing structure is a UV adhesive applied to the exposed surface edge of the splicing seam between adjacent connecting shells, and each adhesive dot spans the adjacent boundary line of the two connecting shells. The UV adhesive is cured under ultraviolet light irradiation to fix the adjacent connecting shells into one piece. The UV adhesive is applied in a dotted manner with intervals, leaving uncoated areas between adjacent adhesive dots. These uncoated areas serve as flexible hinge areas to maintain the flexible bending capability at the joint.

[0013] Furthermore, each of the connecting shells is provided with a limiting protrusion and a limiting groove at the splicing interface, and the two are arranged in a centrally symmetrical manner with respect to the center of the splicing interface. The limiting protrusion and the limiting groove on the adjacent connecting shell form a sliding fit during splicing, so as to achieve preliminary positioning and anti-displacement at the physical level. The limiting protrusion and limiting groove are formed on the connecting shell.

[0014] Furthermore, it also includes a terminal protective cover, which is detachably fitted onto the exposed splicing interface of the connecting shell at the outermost end of the splicing link. The inner end face of the terminal protective cover is provided with an avoidance structure that is adapted to the limiting protrusion and the limiting groove. The terminal protective cover is provided with a short-circuit jumper or bypass resistor inside to ensure the integrity of the electrical circuit when a single flexible line unit is used independently.

[0015] Furthermore, the flexible reinforcing film is a polyimide film or a thermoplastic polyurethane elastomer film, and the flexible reinforcing film is attached to the back of the splicing of the connecting shell, bridging the splicing gap between two adjacent connecting shells.

[0016] Furthermore, the UV adhesive is distributed in the form of dots or short line segments, with the diameter of each adhesive dot being 0.5mm to 2.0mm and the spacing between adjacent adhesive dots being 2.0mm to 8.0mm. The size and spacing of the adhesive dots are set according to the required degree of bending. During disassembly, the UV adhesive dots are cut open using a cutting tool to separate adjacent connecting shells, enabling independent replacement of the flexible circuit unit.

[0017] Furthermore, the conductive lines of each flexible circuit unit include power lines and signal lines, which are arranged in a parallel branch structure inside the flexible circuit unit. The main line runs through both ends of the flexible circuit unit and is used to realize the series transmission of electrical signals in the spliced ​​state. The functional circuit is mounted on the main line through the parallel branches and is used to realize the independent function of the flexible circuit unit in the independent state.

[0018] Furthermore, the insulating layer is an insulating protective film made of polyimide or polyethylene terephthalate, which completely seals and wraps each individual conductive line.

[0019] Furthermore, the cross-sectional shape of the limiting protrusion and the limiting groove is selected from any one of rectangular, trapezoidal, semi-circular or dovetail shapes; When the cross-sectional shape of the limiting protrusion and the limiting groove is rectangular, an anti-reverse insertion structure is also provided at the splicing interface of the adjacent connecting shells. The anti-reverse insertion structure is an asymmetrically arranged guide slope or guide protrusion, which is used to ensure that the adjacent connecting shells can only be spliced ​​in the correct direction.

[0020] As can be seen from the above, the modular flexible circuit board that can be quickly assembled, provided by one or more embodiments of this specification, has the following specific advantages: Quick and easy assembly: Through magnetic guidance and positioning, adjacent connecting shells automatically adhere and align during assembly, allowing for rapid assembly without the need for any manual tools.

[0021] Stable and reliable connection: It adopts a dual splicing mode of "magnetic rapid guidance and positioning and UV adhesive curing and fixing", which ensures both rapid self-alignment during splicing (relying on magnetic force) and high reliability during use (relying on UV adhesive curing).

[0022] Reasonable stress distribution in the splicing area: By moving the magnetic components and limiting structure from the FPC sheet body to the connecting shell, the stress concentration problem caused by machining holes and embedding hard parts in the FPC body is avoided; at the same time, the flexible reinforcing film set on the back of the splice transmits the bending stress from the splice point to the entire reinforcing film area, effectively protecting the splicing area and the FPC body.

[0023] The splicing joints remain flexible: the UV adhesive is applied in a dotted manner at intervals, and the uncoated areas serve as flexible hinge areas, so that the splicing joints still have a certain degree of flexibility and can adapt to the needs of three-dimensional spatial wiring.

[0024] Modules can be used independently: Each flexible circuit unit can be removed and used as a complete independent flexible circuit board to meet the needs of small-scale or single-path wiring.

[0025] Flexible combination and splicing: Multiple flexible line units can be connected in series to form any length as needed, adapting to different sizes and scales of cabling requirements, and achieving flexible expansion in a "building block" style.

[0026] Low maintenance cost and easy operation: The UV adhesive is distributed in a dotted pattern. When disassembling, you only need to cut each adhesive dot with a blade to separate the connection shell. There is no need to rely on chemical reagents or high temperature heating, which avoids the risk of damaging the FPC and components. When a single circuit unit is damaged, only the unit needs to be replaced, without scrapping the entire circuit board. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in one or more embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one or more embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the overall structure of the modular flexible circuit board that can be quickly assembled according to the present invention; Figure 2 This is a schematic diagram of the structure of a single flexible circuit unit and connecting shell of the present invention; Figure 3 This is a schematic diagram of the splicing state of adjacent connecting shells according to the present invention; Figure 4 This is a schematic diagram of the magnetic splicing hole structure on the connecting shell of the present invention.

[0029] In the diagram: 1. Flexible circuit unit; 11. Conductive circuit; 12. Splicing interface; 13. External wiring terminal; 14. Insulating layer; 2. Connecting shell; 21. Limiting protrusion; 22. Limiting groove; 23. Magnetic splicing hole. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments.

[0031] It should be noted that, unless otherwise defined, the technical or scientific terms used in one or more embodiments of this specification should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar words used in one or more embodiments of this specification do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0032] Example 1: like Figure 1 and Figure 2 As shown in the figure, this embodiment provides a modular flexible circuit board that can be quickly assembled, including at least two flexible circuit units 1 arranged sequentially and independently.

[0033] Each flexible circuit unit 1 is fixedly connected to a connecting shell 2 at its end. The connecting shell 2 is injection molded from an insulating material (such as polycarbonate, nylon, liquid crystal polymer, etc.) with a certain strength and moderate flexibility. Its thickness is greater than that of the flexible circuit unit 1, so as to provide sufficient structural strength for the interface structure. The end of the flexible circuit unit 1 is fixedly connected to the connecting shell 2, so that the flexible circuit unit 1 and the connecting shell 2 form an integral component.

[0034] The connecting shell 2 is equipped with a magnetic positioning structure and a UV adhesive bonding and fixing structure for quick assembly. Specifically, the magnetic positioning structure is a magnetic splicing hole 23 located at the corner of the connecting shell 2, and the magnetic splicing hole 23 is equipped with magnetic adsorption elements (N-pole magnet and S-pole magnet). The UV adhesive bonding and fixing structure is UV adhesive on the splicing end face of the connecting shell 2, which is used to fix adjacent connecting shells 2 into one piece after magnetic positioning.

[0035] Each flexible circuit unit 1 includes an internal conductive line 11 and an insulating layer 14 wrapped around the outer surface of the conductive line 11. The insulating layer 14 is an insulating protective film made of polyimide or polyethylene terephthalate. The insulating protective film completely seals and wraps each individual conductive line 11. Polyimide has excellent high temperature resistance and good mechanical strength, while polyethylene terephthalate has the advantages of low cost and good transparency.

[0036] Each flexible circuit unit 1 has an external terminal block 13 at one end for connecting to external electronic components. The external terminal block 13 is a gold finger structure or a pin structure, located at one end of the flexible circuit unit 1 along its length, for mating with the connector of an external device. The other end forms a splicing interface 12 through a connecting shell 2 for splicing with adjacent flexible circuit units 1.

[0037] The flexible circuit unit 1 is also provided with at least one mounting hole, which is opened on the insulating isolation layer 14 and avoids the area of ​​the conductive line 11, for fixing the spliced ​​flexible circuit board as a whole or the independent flexible circuit unit 1 to the external equipment housing.

[0038] Each flexible circuit unit 1 is sequentially spliced ​​together through the connecting shell 2 to form a chain-type circuit board as a whole; each flexible circuit unit 1 can be used as a complete flexible circuit board in an independent state.

[0039] A flexible reinforcing film is also provided on the back of the splice of the connecting shell 2. The flexible reinforcing film is a polyimide film or a thermoplastic polyurethane elastomer film, which is attached to the back of the splice of the connecting shell 2 with an adhesive, bridging the splice gap between two adjacent connecting shells 2. The setting of the flexible reinforcing film allows the stress at the splice to be transferred from the edge of the connecting shell 2 to the flexible reinforcing film when the circuit board is bent as a whole. The deformation of the flexible reinforcing film disperses the stress to its entire area, effectively reducing the local stress concentration at the splice and protecting the conductive lines 11 and UV adhesive from damage.

[0040] Example 2: Magnetic Positioning and Splicing Structure like Figure 2 , Figure 3 and Figure 4 As shown, this embodiment provides a detailed description of the magnetic positioning structure based on Embodiment 1.

[0041] The magnetic positioning structure is a magnetic splicing hole 23 located at the corner of the connecting shell 2. The magnetic splicing hole 23 is equipped with a magnetic adsorption element, which is used to automatically adsorb, align and position adjacent connecting shells 2 by magnetic force during splicing.

[0042] Specifically, the magnetic adsorption element includes an N-pole magnet and a S-pole magnet, such as Figure 4 As shown, N-pole magnets and S-pole magnets are arranged in pairs at the corresponding corner positions of adjacent connecting shells 2. That is, an N-pole magnet is set at the corner of the splicing end of the first connecting shell 2, and an S-pole magnet is set at the corresponding corner of the splicing end of the second connecting shell 2. When adjacent connecting shells 2 are spliced, the N-pole magnets and S-pole magnets attract each other to achieve automatic alignment and positioning.

[0043] The magnetic splicing hole 23 is opened at the corner of the connecting shell 2. It is a circular through hole or a blind hole. The N pole magnet and the S pole magnet can be made of neodymium iron boron permanent magnet material or ferrite permanent magnet material. Neodymium iron boron magnet has the advantages of high magnetic energy product and small size, and is suitable for use in miniaturized connecting shells; ferrite magnet has the characteristics of low cost and good corrosion resistance.

[0044] The magnets are installed using an embedded method, meaning that magnetic splicing holes 23 are made at the corners of the connecting shell 2. The magnets are pressed into or glued into the magnetic splicing holes 23, with the surface of the magnets flush with or slightly lower than the surface of the connecting shell 2 to avoid interference during splicing. The magnetic poles of the magnets are set along the splicing direction, with the N pole facing outwards from the splicing end face and the S pole facing inwards from the splicing end face, or vice versa, to ensure that adjacent connecting shells 2 generate an attractive force rather than a repulsive force when they are close together.

[0045] One of the key improvements of this invention is that the magnet is placed on the connecting shell 2 instead of being directly embedded in the flexible circuit unit 1. Since the connecting shell 2 has a certain thickness and strength, the embedding of the magnet will not cause stress concentration in the FPC sheet, and the junction between the magnet and the substrate will not damage the conductive circuit 11 when bending.

[0046] In actual splicing operations, when the operator brings the splicing ends of the two connecting shells 2 close to each other to an appropriate distance, the magnetic attraction between the N-pole magnet and the S-pole magnet begins to play a role, automatically pulling the two connecting shells 2 closer and aligning them, so that the limiting protrusion 21 accurately slides into the limiting groove 22 of the adjacent connecting shell 2. This process does not require manual fine alignment, which greatly improves splicing efficiency and splicing accuracy.

[0047] The magnetic force of the magnet should be reasonably designed according to the size and weight of the connecting shell 2 and the flexible circuit unit 1, so as to achieve effective automatic positioning without causing operational difficulties due to excessive attraction.

[0048] Example 3: Sliding fit structure of limiting protrusion and limiting groove like Figure 3 As shown, this embodiment provides a detailed description of the physical positioning structure based on Embodiment 1 and Embodiment 2.

[0049] Each connecting shell 2 has a limiting protrusion 21 and a limiting groove 22 at its splicing interface 12, and the two are arranged symmetrically with respect to the center of the splicing interface 12. When adjacent connecting shells 2 are spliced, the limiting protrusion 21 on one connecting shell 2 and the limiting groove 22 on the other connecting shell 2 form a sliding fit, realizing the initial positioning and anti-displacement at the physical level. The limiting protrusion 21 and the limiting groove 22 are formed on the connecting shell 2, rather than directly formed on the thin plate body of the flexible circuit unit 1.

[0050] The placement of the limiting structure on the connecting shell 2 is another key improvement of this invention. The flexible circuit unit 1 is extremely thin, making direct machining of bumps or grooves not only extremely difficult and costly, but also resulting in insufficient strength of the molded bump structure, making it prone to wear or breakage during use. In contrast, the connecting shell 2 is manufactured using injection molding, allowing for the low-cost and high-precision machining of various shapes of limiting bumps 21 and limiting grooves 22, while maintaining sufficient structural strength. More importantly, each connecting shell 2 simultaneously possesses both bumps and grooves arranged symmetrically at the center, enabling the bumps and grooves to mate regardless of orientation between any two connecting shells 2, thus truly achieving the modular design goal of "any two flexible circuit units can be spliced ​​together."

[0051] The cross-sectional shape of the limiting protrusion 21 and the limiting groove 22 is selected from any one of rectangular, trapezoidal, semi-circular, or dovetail shapes. Among them, the rectangular cross-section is simple to process and low in cost; the trapezoidal and dovetail cross-sections have a self-locking effect and are not easy to separate in the direction perpendicular to the splicing direction after splicing; the semi-circular cross-section has good guidance and low insertion force. When the cross-sectional shape of the limiting protrusion 21 is trapezoidal or dovetail, it itself has the function of preventing reverse insertion.

[0052] The limiting protrusion 21 extends along the splicing direction, and the extending direction of the limiting groove 22 is consistent with that of the limiting protrusion 21. The length and height of the limiting protrusion 21 are reasonably set according to the width and thickness of the connecting shell 2. The size of the limiting groove 22 matches that of the limiting protrusion 21. The two are fitted with a clearance fit to facilitate insertion and removal, or an interference fit can be used to enhance the connection firmness.

[0053] During the actual splicing process, the sliding insertion of the limiting protrusion 21 along the limiting groove 22 plays a guiding and limiting role, ensuring the precise alignment of adjacent connecting shells 2 in the splicing direction and preventing offset and misalignment after splicing.

[0054] Example 4: UV adhesive bonding and fixing to the flexible hinge area This embodiment provides a detailed description of the UV adhesive bonding and fixing structure, based on embodiments one to three.

[0055] The UV adhesive bonding and fixing structure consists of UV adhesive applied to the exposed surface edges of the joint between adjacent connecting shells 2, with each adhesive dot spanning the adjacent boundary lines of the two connecting shells 2. The UV adhesive cures under ultraviolet light, fixing the adjacent connecting shells 2 into one unit.

[0056] UV adhesives are either light-curing acrylic adhesives or epoxy resin light-curing adhesives. Light-curing acrylic adhesives have the advantages of fast curing speed, high bonding strength, and good transparency; while epoxy resin light-curing adhesives have higher heat resistance and chemical corrosion resistance, making them suitable for use in harsh environments.

[0057] The UV adhesive is applied in a dotted pattern, meaning it is distributed in dots or short line segments along the exposed edges of the seam of the connecting shell 2. Uncoated areas are left between adjacent dots, serving as flexible hinge zones to maintain the joint's flexibility. The diameter of each adhesive dot ranges from 0.5mm to 2.0mm, and the spacing between adjacent dots ranges from 2.0mm to 8.0mm. The size and spacing of the dots are determined based on the required bending angle: for applications requiring a larger bending angle, the dot size can be reduced or the dot spacing increased, thereby increasing the proportion of the flexible hinge zone; for applications requiring higher joint strength, the dot size can be increased or the dot spacing decreased.

[0058] This intermittent dot coating method solves the problem of the splicing area becoming completely rigid and unable to be bent due to the traditional full-coat UV adhesive. When the spliced ​​circuit board is bent as a whole, the uncoated area acts as a flexible hinge and bends, while the UV adhesive dots provide adhesive fixing force. The two work together to ensure that the splicing joint maintains a certain degree of flexibility while having sufficient connection strength.

[0059] UV adhesive can be applied by dispensing or screen printing. Before applying UV adhesive, the splicing edge surface of the connecting shell 2 should be cleaned to remove oil and dust to ensure bonding strength.

[0060] During the splicing process, adjacent connecting shells 2 are first automatically attracted and aligned by magnetic force. Then, UV adhesive is applied at intervals to the exposed edges of the splicing seam, and then UV adhesive is cured by UV irradiation. This process of "magnetic positioning first, then UV curing" ensures both rapid alignment during splicing and firm fixation after splicing.

[0061] When it is necessary to disassemble or replace a flexible circuit unit 1, simply use a cutting tool such as a blade to cut the UV adhesive dots that cross the adjacent boundary lines from the outside of the connecting shell 2. This will separate the adjacent connecting shells 2 and allow the target flexible circuit unit 1 to be removed. This disassembly method does not rely on chemical reagents or high-temperature heating, is simple and quick to operate, and will not damage the FPC body or electronic components. After replacing the new flexible circuit unit 1, the UV adhesive can be reapplied and cured to complete the repair.

[0062] Example 5: Flexible Reinforcing Membrane Structure This embodiment provides a detailed description of the flexible reinforcing membrane, based on embodiments one through four.

[0063] A flexible reinforcing membrane is provided on the back of the splicing of the connecting shell 2. The flexible reinforcing membrane spans the splicing of two adjacent connecting shells 2 and is used to transfer and disperse stress from the splicing to the flexible reinforcing membrane when the circuit board is bent as a whole after splicing.

[0064] The flexible reinforcing membrane is either a polyimide membrane or a thermoplastic polyurethane elastomer membrane. Polyimide membranes have excellent heat resistance and mechanical strength, making them suitable for use in high-temperature environments; thermoplastic polyurethane elastomer membranes have excellent flexibility and elastic recovery, making them suitable for applications requiring repeated bending. The thickness of the flexible reinforcing membrane is determined based on the required reinforcement effect and flexibility requirements.

[0065] The flexible reinforcing membrane is adhered to the back of the connecting shell 2 using an adhesive, bridging the joint between two adjacent connecting shells 2. The adhesive can be an acrylic pressure-sensitive adhesive or a thermosetting epoxy adhesive, applied to the bonding surface of the flexible reinforcing membrane.

[0066] When the assembled circuit board bends, the bending stress first acts at the splicing seam. Since the flexible reinforcing film spans the splicing seam, the stress is transferred from the edge of the connecting shell 2 to the flexible reinforcing film. The tensile or compressive deformation of the flexible reinforcing film disperses the stress throughout its entire area, thus preventing stress concentration at the splicing seam. This stress dispersion mechanism effectively protects the conductive lines 11 and the UV adhesive from damage, significantly improving the bending life of the splicing area.

[0067] The flexible reinforcing membrane and the intermittent application of UV adhesive work together to ensure the flexibility of the joint. The uncoated areas of the UV adhesive provide flexibility for bending, while the flexible reinforcing membrane provides stress buffering and structural continuity during bending. The two work synergistically to achieve excellent mechanical properties of "flexibility within fixation and support within flexibility".

[0068] Example 6: Terminal Protective Cover and Independent Use Mode This embodiment, based on embodiments one to five, provides a detailed description of the independent usage mode of the flexible circuit unit 1.

[0069] The invention also includes a terminal protective cover, which is detachably fitted onto the exposed splicing interface 12 of the connecting shell 2 at the outermost end of the splicing link. The inner end face of the terminal protective cover is provided with a clearance structure (clearance groove or clearance hole) that matches the limiting protrusion 21 and the limiting groove 22, ensuring that the inner end face of the terminal protective cover fits tightly with the splicing end face of the connecting shell 2 after it is closed. The terminal protective cover is provided with a short-circuit jumper or bypass resistor to ensure the integrity of the electrical circuit when a single flexible line unit 1 is used independently.

[0070] When the user only needs to use a single flexible circuit unit 1, the terminal protective cover can be fastened to the splicing interface 12 end of the connecting shell 2 of the flexible circuit unit 1. The short-circuit jumper inside the terminal protective cover short-circuit the end of the conductive line 11 (for circuits that need to form a loop) or perform terminal matching through a bypass resistor (for high-frequency signal transmission lines), ensuring the integrity of the electrical circuit and enabling the flexible circuit unit 1 to work independently.

[0071] The terminal protective cover can be injection molded from insulating plastic, with an embedded conductive metal sheet or resistive element. The splicing interface 12 between the terminal protective cover and the connecting shell 2 can be engaged by snap-fit ​​or magnetic attraction, facilitating quick installation and removal.

[0072] When multiple flexible circuit units 1 need to be spliced ​​together, simply remove the terminal protective cover of each flexible circuit unit 1, and then connect the splicing interfaces 12 of each connecting shell 2 in sequence. This design allows the same flexible circuit unit 1 to be used independently or as part of a whole in combined mode, realizing the function of "one thing serving two purposes".

[0073] Example 7: Anti-reverse insertion structure like Figure 2 and Figure 3 As shown, this embodiment provides a detailed description of the anti-reverse insertion structure based on embodiments one through six.

[0074] When the cross-sectional shape of the limiting protrusion 21 and the limiting groove 22 is rectangular (i.e., symmetrical vertically and without self-anti-reverse insertion capability), an anti-reverse insertion structure is also provided at the splicing interface 12 of the adjacent connecting shell 2. The anti-reverse insertion structure is an asymmetrically arranged guide slope or guide protrusion, used to ensure that the adjacent connecting shell 2 can only be spliced ​​in the correct direction.

[0075] There are several ways to implement the anti-reverse insertion structure. One way is to set an asymmetrical cross-sectional shape on the limiting protrusion 21 and the limiting groove 22. For example, the cross-section of the limiting protrusion 21 is set to an asymmetrical trapezoid (when the cross-sectional shape itself is asymmetrical), and the cross-section of the limiting groove 22 matches it. If the operator tries to splice in reverse, the limiting protrusion 21 cannot enter the limiting groove 22.

[0076] Another approach is to install a guide ramp on one side of the splicing interface 12, while leaving it uninstalled on the other side. When the operator splices in the correct direction, the guide ramp guides the splicing smoothly; when the operator splices in the wrong direction, the guide ramp interferes with the opposite structure, preventing splicing. The anti-reverse insertion structure effectively avoids electrical connection errors caused by incorrect splicing direction (such as reversed power supply polarity, misaligned signal lines, etc.), improving the safety and reliability of the splicing. When the cross-sectional shape of the limiting protrusion 21 is itself asymmetrical (such as trapezoidal or dovetail), it inherently possesses anti-reverse insertion functionality, eliminating the need for an additional anti-reverse insertion structure.

[0077] Example 8: "Straight-through and Branch" Design of Electrical Circuits like Figure 1 and Figure 2As shown, this embodiment provides a detailed description of the internal electrical circuit design of the flexible circuit unit 1, based on embodiments one through seven.

[0078] Each flexible circuit unit 1 has conductive lines 11 including power lines and signal lines. The power lines and signal lines are arranged in parallel branch structure inside the flexible circuit unit 1. The main line runs through both ends of the flexible circuit unit 1 and is used to realize the series transmission of electrical signals in the spliced ​​state; the functional circuit is mounted on the main line through parallel branches and is used to realize the independent function of the flexible circuit unit 1 in the independent state.

[0079] Specifically, the power lines (including positive and negative / ground lines) and signal lines in the conductive line 11 enter from one end of the flexible line unit 1 (external terminal 13) and extend along the length of the flexible line unit 1 to the other end (splitter interface 12), forming a "straight-through" main line. Along the main line, power and signals are led to electronic components (such as LED beads, sensor chips, resistors, capacitors, etc.) installed on the flexible line unit 1 through branch lines. These branch lines are connected in parallel with the main line.

[0080] This "straight-through, branching" circuit design allows power and signals to be transmitted sequentially from the main line of the first flexible circuit unit 1 to the last flexible circuit unit 1 in the spliced ​​state, with all functional circuits on the flexible circuit unit 1 working synchronously; in the independent state, simply sealing the interfaces at both ends of a single flexible circuit unit 1 with a terminal protective cover forms a loop in the main line, and the flexible circuit unit 1 can operate independently.

[0081] Example 9: Splicing and combining multiple flexible circuit units This embodiment provides a detailed description of the splicing and combination of multiple flexible circuit units 1.

[0082] In practical use, users can select any number of flexible line units 1 to splice together as needed.

[0083] The splicing operation steps are as follows: The first step is to select the appropriate number and specifications of flexible wiring units 1 based on actual wiring requirements.

[0084] The second step is to remove the terminal protection cover of each flexible line unit 1.

[0085] The third step is to align the splicing interface 12 of the first connecting shell 2 with the splicing interface 12 of the second connecting shell 2, so that the limiting protrusion 21 on one connecting shell 2 is aligned with the limiting groove 22 on the other connecting shell 2, and the N pole magnet is aligned with the S pole magnet.

[0086] The fourth step is to bring the two connecting shells 2 close to each other. Under the action of magnetic force, the two automatically attract and align, and the limiting protrusion 21 slides into the limiting groove 22 to complete the initial positioning.

[0087] The fifth step is to apply UV adhesive in a dotted manner at intervals along the exposed edges of the splicing seams, with each adhesive dot spanning the adjacent boundary lines of the two connecting shells 2. Then, use ultraviolet light to cure the UV adhesive and complete the fixation.

[0088] Step 6: Repeat the above steps to connect all the flexible circuit units 1 that need to be spliced ​​in series.

[0089] Step 7: Secure the assembled circuit board to the external device housing through the mounting holes, and connect the external terminal block 13 to the external device connector to complete the overall installation.

[0090] The assembled circuit board maintains good flexibility at the connection shell 2 through the combined action of the uncoated area and the flexible reinforcing film. It can be bent and folded as a whole to adapt to complex three-dimensional installation spaces. The splice has sufficient mechanical strength to withstand a certain degree of bending and vibration and will not loosen during use.

[0091] When it is necessary to replace a flexible circuit unit 1, use a blade to cut open the UV adhesive dots at the edge of the exposed surface of the splicing seam on both sides of the connecting shell 2 from the outside of the unit (each adhesive dot spans the adjacent boundary line, and the blade can be cut directly from the outside), remove the damaged unit, connect the new flexible circuit unit 1 to the original position, reapply UV adhesive and cure it, without scrapping the entire circuit board.

[0092] Example 10: Manufacturing Process This embodiment provides a detailed description of the manufacturing method of the modular flexible circuit board that can be quickly assembled according to the present invention.

[0093] The manufacturing method includes the following steps: Step 1: Prefabrication of flexible circuit units. Copper foil is selected as the conductive material, and the pattern of conductive circuit 11 is made on a temporary carrier by etching or laser micro-cladding. An insulating protective film of polyimide or polyethylene terephthalate is wrapped on the outer surface of conductive circuit 11 by hot pressing or coating to form an insulating isolation layer 14. An external terminal 13 is made at one end of the flexible circuit unit 1, and mounting holes are processed at predetermined positions (avoiding the conductive circuit area).

[0094] Step 2: Injection molding of the connecting shell. Using injection molding process, materials such as polycarbonate, nylon or liquid crystal polymer are used to integrally mold the connecting shell 2. The connecting shell 2 has pre-reserved structures such as magnetic splicing holes 23, limiting protrusions 21, limiting grooves 22 and guide slopes. The splicing end face of the connecting shell 2 has pre-reserved UV adhesive coating grooves.

[0095] Step 3: Magnet installation. Press or glue the N-pole magnet or S-pole magnet into or onto the magnetic splicing hole 23 of the connecting shell 2, with the magnet surface flush with the surface of the connecting shell 2.

[0096] Step 4: Assemble the flexible circuit unit and the connecting shell. Fix the end of the flexible circuit unit 1 to the connecting shell 2 by heat pressing or bonding, so that the end of the conductive circuit 11 corresponds to the splicing interface 12 of the connecting shell 2.

[0097] Step 5: Flexible reinforcing membrane bonding. A flexible reinforcing membrane is bonded to the back of the splicing of the connecting shell 2 using adhesive. The flexible reinforcing membrane spans the splicing gap of adjacent connecting shells 2.

[0098] Step 6: Electronic component mounting. According to functional requirements, electronic components are soldered onto the flexible circuit unit 1 using surface mount technology.

[0099] Step 7: Terminal protection cover is made by injection molding. The terminal protection cover is embedded with a short-circuit jumper or bypass resistor. The inner end face of the terminal protection cover is provided with an avoidance structure that matches the limiting protrusion 21 and the limiting groove 22.

[0100] Step 8: Testing and Inspection. Conduct electrical and mechanical performance tests on the completed flexible circuit unit 1 and connecting shell 2 components to ensure product qualification.

[0101] Example 11: Mixed assembly of modules of different specifications To enable the mixed-use splicing of different functional modules, the splicing interfaces 12 of all connecting shells 2 adopt a unified standardized design. That is, each connecting shell 2 is equipped with limiting protrusions 21 and limiting grooves 22, which are arranged symmetrically in a central manner. The position and polarity of the magnets are uniform, and the external dimensions of the splicing interfaces 12 are consistent in all connecting shells 2. In this way, no matter how different the internal circuits and functions of each flexible circuit unit 1 are, their physical interfaces are unified, and any two flexible circuit units 1 can be spliced ​​together.

[0102] Example 12: Optional Reinforced Fixation Method In some scenarios where connection reliability is extremely important, through holes can be made on the connecting shell 2 after UV adhesive curing. After the splicing is completed, mechanical locking is achieved by passing bolts or rivets through the through holes.

[0103] Example 13: Signal Relay and Long-Distance Transmission Signal relay chips can be integrated into some flexible line units 1. These flexible line units 1 with relay functions have the same connection shell 2 interface as ordinary units and can be inserted into any position in the splicing link to effectively compensate for signal attenuation caused by long-distance transmission.

[0104] Example 14: Multi-layer stacking and splicing Splicing interfaces 12 are provided on the upper and lower surfaces of the connecting shell 2 of the flexible circuit unit 1, so that a flexible circuit unit 1 can be spliced ​​horizontally or stacked vertically, realizing arbitrary expansion in three-dimensional space.

[0105] Example 15: Combined use with rigid circuit boards The flexible circuit unit 1 is connected to the FPC connector on the rigid printed circuit board through the external terminal block 13, so as to realize the electrical connection between the flexible circuit board and the rigid circuit board and give full play to the advantages of both.

[0106] Application scenarios and environmental adaptability: For high-temperature environments, the connecting shell 2 is made of high-temperature resistant liquid crystal polymer material, the insulating layer 14 is made of polyimide, the UV adhesive is made of high-temperature resistant epoxy resin, and the magnet is made of samarium cobalt magnet; for humid environments, a waterproof coating and sealing ring are added; for environments with electromagnetic interference shielding requirements, a conductive shielding layer is added.

[0107] The modular flexible circuit board of this invention, which can be quickly assembled, can be widely used in the following scenarios: Scenario 1: Internal wiring of large equipment. When long-distance wiring is required inside large equipment, multiple flexible wiring units 1 are spliced ​​together to achieve ultra-long wiring.

[0108] Scenario 2: Consumer electronics products, such as smartphones, tablets, and wearable devices, enabling flexible circuit layouts and convenient repair and replacement.

[0109] Scenario 3: Automotive electronic systems, such as door wiring harnesses and seat sensors, require vibration resistance and dynamic bending resistance. The magnetic positioning and UV adhesive on the connecting shell 2 provide a highly reliable connection.

[0110] Scenario 4: Flexible sensor array. In large-area flexible sensors such as electronic skin and smart textiles, the units are spliced ​​together to form a complete sensor array. When a single sensor is damaged, only the corresponding flexible circuit unit 1 needs to be replaced.

[0111] Scenario 5: Lighting module. In the long strip LED lighting module, light strips of any length can be spliced ​​together. When a single LED bead is damaged, only the corresponding flexible circuit unit 1 needs to be replaced.

[0112] Scenario 6: Scientific research and teaching experiments. In scientific research and teaching experiments related to electronic engineering, flexible selection and combination of flexible circuit units 1 with different functions can be used to quickly build experimental circuits.

[0113] Industrial Applicability: The modular flexible circuit board provided by this invention, which can be quickly assembled, has a reasonable structural design, mature manufacturing process, and is easy to use and operate, thus possessing excellent industrial applicability. Each flexible circuit unit 1 and connecting shell 2 can be mass-produced in a standardized manner; the assembly and installation process requires no special tools, making it suitable for large-scale promotion and application. This invention can be widely used in multiple fields such as consumer electronics, automotive electronics, industrial control, smart homes, and medical devices, and has good market prospects and economic benefits.

[0114] Verification of the effectiveness of specific implementation methods To verify the technical effects of this invention, the applicant conducted the following experiments: Verification 1: Splicing accuracy test. Using the magnetic positioning splicing structure of this invention, splicing tests were conducted on multiple sets of connecting shells 2. The results show that, under magnetic guidance, adjacent connecting shells 2 can quickly and automatically complete alignment. The splicing operation time is significantly shorter than that of the traditional manual alignment method, and the splicing consistency is good.

[0115] Verification 2: Bending life test at the splicing joint. Using the method of applying UV adhesive at intervals (adhesive dots diameter 0.5mm~2.0mm, spacing 2.0mm~8.0mm) in conjunction with the flexible reinforcing film of the present invention, the spliced ​​flexible circuit board was subjected to repeated bending tests. The results showed that no cracking, peeling or breakage of the UV adhesive or conductive line 11 occurred at the splicing joint after repeated bending. The bending life was better than that of the full UV adhesive coating method.

[0116] Verification 3: Independent Use Test. After installing a terminal protection cover, each flexible circuit unit 1 was powered on and operated independently. All test samples were able to work normally, verifying the feasibility of "single module independent operation".

[0117] Verification 4: Replacement and maintenance test. A single flexible circuit unit 1 was simulated to be damaged in the splicing link. The replacement method of the present invention was followed (cutting the UV adhesive dot from the outside of the connecting shell with a blade, taking out the damaged unit, replacing it with a new unit, and reapplying adhesive for curing). The results showed that the replacement operation was simple and quick, without the need for chemical reagents or high-temperature heating. After the replacement, the overall circuit board function was restored to normal.

[0118] The above verification results show that the present invention has achieved the expected technical effects in terms of splicing efficiency, splicing area bending reliability, independent use and maintenance convenience.

[0119] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this disclosure (including the claims) is limited to these examples; within the framework of this disclosure, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this specification as described above, which are not provided in detail for the sake of brevity.

[0120] Although this disclosure has been described in conjunction with specific embodiments thereof, many substitutions, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description.

[0121] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this disclosure (including the claims) is limited to these examples; within the framework of this disclosure, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this specification as described above, which are not provided in detail for the sake of brevity.

[0122] Although this disclosure has been described in conjunction with specific embodiments thereof, many substitutions, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description.

[0123] One or more embodiments of this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of this specification should be included within the scope of protection of this disclosure.

Claims

1. A modular flexible circuit board that can be quickly assembled, comprising at least two sequentially arranged and independently configured flexible circuit units (1), characterized in that: Each of the flexible circuit units (1) is fixedly connected to a connecting shell (2) at its end. The connecting shell (2) is provided with a magnetic positioning structure and a UV adhesive bonding and fixing structure for quick splicing. Each of the flexible circuit units (1) includes an internal conductive line (11) and an insulating layer (14) wrapped around the outer surface of the conductive line (11). Each of the flexible circuit units (1) has an external terminal (13) for connecting to external electronic components at one end, and a splicing interface (12) for splicing with adjacent flexible circuit units (1) is formed at the other end of the connecting shell (2). The flexible circuit unit (1) is sequentially spliced ​​together through the connecting shell (2) to form a chain circuit board as a whole. Each of the flexible circuit units (1) can be used as a complete flexible circuit board in an independent state. The back of the splicing of the connecting shell (2) is also provided with a flexible reinforcing membrane. The flexible reinforcing membrane is connected across the splicing of two adjacent connecting shells (2) and is used to transfer and disperse the stress from the splicing to the flexible reinforcing membrane when the circuit board is bent as a whole after splicing.

2. The modular flexible circuit board that can be quickly assembled according to claim 1, characterized in that, The magnetic positioning structure is a magnetic splicing hole (23) set at the corner of the connecting shell (2). The magnetic splicing hole (23) is provided with a magnetic adsorption element, which is used to automatically adsorb, align and position the adjacent connecting shells (2) by magnetic force during splicing. The magnetic adsorption element includes an N-pole magnet and an S-pole magnet, which are arranged in pairs at corresponding corner positions of adjacent connecting shells (2).

3. The modular flexible circuit board that can be quickly assembled according to claim 1, characterized in that, The UV adhesive bonding and fixing structure is a UV adhesive applied to the exposed surface edge of the splicing gap between adjacent connecting shells (2), and each adhesive dot spans the adjacent boundary line of the two connecting shells (2). The UV adhesive is cured under ultraviolet light irradiation to fix the adjacent connecting shells (2) into one piece. The UV adhesive is applied in a dotted manner with intervals, leaving uncoated areas between adjacent adhesive dots. These uncoated areas serve as flexible hinge areas to maintain the flexible bending capability at the joint.

4. The modular flexible circuit board that can be quickly assembled according to claim 1, characterized in that, Each of the connecting shells (2) has a limiting protrusion (21) and a limiting groove (22) at the splicing interface (12), and the two are arranged in a centrally symmetrical manner with respect to the center of the splicing interface (12). The limiting protrusion (21) and the limiting groove (22) on the adjacent connecting shell (2) form a sliding fit during splicing to achieve preliminary positioning and anti-displacement at the physical level. The limiting protrusion (21) and limiting groove (22) are formed on the connecting shell (2).

5. A modular flexible circuit board that can be quickly assembled according to claim 1, characterized in that, It also includes a terminal protection cover, which is detachably fitted onto the exposed splicing interface (12) of the connecting shell (2) at the outermost end of the splicing link. The inner end face of the terminal protection cover is provided with a clearance structure that is adapted to the limiting protrusion (21) and the limiting groove (22). The terminal protection cover is provided with a short-circuit jumper or bypass resistor inside to ensure the integrity of the electrical circuit when a single flexible line unit (1) is used independently.

6. A modular flexible circuit board that can be quickly assembled according to claim 1, characterized in that, The flexible reinforcing film is a polyimide film or a thermoplastic polyurethane elastomer film. The flexible reinforcing film is attached to the back of the splicing of the connecting shell (2) and spans the splicing gap of two adjacent connecting shells (2).

7. A modular flexible circuit board that can be quickly assembled according to claim 3, characterized in that, The UV adhesive is distributed in dots or short line segments at intervals, with the diameter of each adhesive dot being 0.5mm to 2.0mm and the spacing between adjacent adhesive dots being 2.0mm to 8.0mm. The size and spacing of the adhesive dots are set according to the required degree of bending. During disassembly, the UV adhesive dots are cut open using a cutting tool to separate adjacent connecting shells (2), thereby enabling independent replacement of the flexible circuit unit (1).

8. A modular flexible circuit board that can be quickly assembled according to claim 1, characterized in that, Each of the flexible circuit units (1) has a conductive line (11) including a power line and a signal line. The power line and the signal line are in a parallel branch structure inside the flexible circuit unit (1). The main line runs through both ends of the flexible circuit unit (1) and is used to realize the series transmission of electrical signals in the spliced ​​state. The functional circuit is mounted on the main line through the parallel branches and is used to realize the independent function of the flexible circuit unit (1) in the independent state.

9. A modular flexible circuit board that can be quickly assembled according to claim 1, characterized in that, The insulating layer (14) is an insulating protective film made of polyimide or polyethylene terephthalate, which completely seals and wraps each individual conductive line (11).

10. A modular flexible circuit board that can be quickly assembled according to claim 4, characterized in that, The cross-sectional shape of the limiting protrusion (21) and the limiting groove (22) is selected from any one of rectangular, trapezoidal, semi-circular or dovetail shapes; When the cross-sectional shape of the limiting protrusion (21) and the limiting groove (22) is rectangular, an anti-reverse insertion structure is also provided at the splicing interface (12) of the adjacent connecting shell (2). The anti-reverse insertion structure is an asymmetrically arranged guide slope or guide protrusion, which is used to ensure that the adjacent connecting shell (2) can only be spliced ​​in the correct direction.

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