Light source module applied to key core and manufacturing method

Abstract

The invention relates to the technical field of connecting structures of flexible printed circuits, and discloses a light source module applied to a key core and a manufacturing method of the light source module, the light source module comprises a flexible substrate and a plurality of light emitting diodes, a first circuit area, a buffer area and a second circuit area are sequentially formed on a connecting part of the flexible substrate, the buffer area is not provided with a conductive circuit and is only used for mechanical connection, when the buffer area is not in a bent state, the first circuit area and the second circuit area are in an open circuit state, the first circuit area and the second circuit area are isolated by the buffer area, and the first circuit area and the second circuit area do not establish an electrical conduction relation; and bending the second circuit area towards the first circuit area through the buffer area, so that the buffer area is in a bent state, and electrically connecting the second circuit area to the first circuit area through the conductive adhesive. The problem of fatigue caused by traditional reflexion can be avoided, the structural reliability and the module integration degree are improved, and the keyboard module is suitable for products such as thin keyboards.

Description

Technical Field

[0001] The present application relates to the technical field of connection structures of flexible printed circuits, and in particular to a light source module applied to a key core and a manufacturing method thereof. Background Art

[0002] As electronic products develop towards thinner, smaller, and more modular designs, flexible printed circuits (FPCs) are widely used in laptops, tablets, wearable devices, and other products due to their excellent bendability and high degree of structural freedom. They play a particularly critical role in the light source introduction structure of keyboard modules.

[0003] In existing technology, keyboard backlight modules often use a "reverse folding structure" to connect the FPC to the underlying circuit board. This involves partially bending or flipping the FPC so that its soldered end forms an electrical connection with the motherboard or control board on the keyboard base. While this structure can achieve spatial conductivity, it presents the following technical issues: The circuits in the bends are prone to fatigue cracking: after prolonged use, the bending stress in the bend area is easily concentrated at the soldering points or the bend angles of the circuits, leading to fractures or poor solder joints. High assembly complexity: the bending, positioning, and soldering of the circuits require the coordination of precision jigs, increasing the difficulty and cost of the production process. Limited reliability: some bend structures are prone to solder joint warping or electrical instability when subjected to impact or thermal expansion and contraction. Limited structural packaging: the bend-backed circuits are difficult to integrate with the overall keycap structure or thin-film circuit design, making it difficult to meet the requirements of thin or modular designs. In addition, some current technologies use tape to fix FPC wiring or use reserved sockets for conductivity, but these methods often require additional space, have poor stability, and are difficult to support large-scale automated processes.

[0004] Therefore, a new light source module structure and its manufacturing method are urgently needed, which can achieve both electrical conduction and mechanical connection without relying on the inflection structure, and improve the overall structural strength and production yield of the module. Summary of the Invention

[0005] This application aims to overcome the problems of structural fatigue, complex assembly and unstable conductivity caused by the FPC folded connection of the keyboard backlight module in the prior art, and to provide a light source module for the key core with reliable structure, stable conductivity and suitable for modular design, and its manufacturing method.

[0006] The present application provides a light source module for a key core, comprising: a flexible substrate having a light-emitting portion and a connecting portion extending from one side of the light-emitting portion; a plurality of light-emitting diodes arranged equidistantly on the light-emitting portion; the connecting portion sequentially including a first circuit area, a buffer area, and a second circuit area from one side of the light-emitting portion; wherein the buffer area is not provided with a conductive circuit and is used to provide a flexible mechanical connection function; the first circuit area forms a mechanical connection relationship with the second circuit area through the buffer area, and when the buffer area is not in a bent state, the first circuit area and the second circuit area are in an open circuit state, the first circuit area and the second circuit area are isolated by the buffer area, and the first circuit area and the second circuit area do not establish an electrical conduction relationship; the second circuit area is bent toward the first circuit area through the buffer area, so that the buffer area is in a bent state, and the second circuit area is electrically connected to the first circuit area through a conductive adhesive. Since the electrical conduction relationship of the entire circuit of the present application is established after the circuit is folded back, it is different from the traditional structure in which the electrical conduction relationship is formed and then bent according to assembly needs. Therefore, the structure of this application avoids the circuit breakage and stress concentration problems caused by flexing in traditional FPC structures (interfaces of different materials or solder joints are often structurally vulnerable areas). This ensures mechanical stability and electrical reliability of the flexible conductive path within the light source module, while also reducing solder joints and plug-in structures, increasing automated assembly rates, and simplifying the overall production process. Furthermore, it mitigates the risk of failure caused by thermal expansion and contraction at interfaces or solder joints, or by long-term mechanical stress, thereby extending the module's service life and impact resistance.

[0007] Preferably, the first and second circuit areas each have openings to expose the solder pads. Conductive adhesive is applied through these openings to connect to the corresponding solder pads, thereby achieving electrical continuity. This overcomes the reliability issues inherent in conventional structures caused by bending the circuits. Furthermore, a reinforcement plate can be provided in the buffer zone to further enhance structural strength.

[0008] The present application also provides a method for manufacturing a light source module for a key core, the method being used to manufacture the light source module for a key core as described in any one of the above items, the method comprising the following steps: providing a flexible substrate, the substrate having a light-emitting portion and a connecting portion extending from one side thereof, the connecting portion comprising a first circuit area, a buffer area and a second circuit area; arranging a plurality of equidistantly arranged light-emitting diodes on the light-emitting portion; the buffer area is not provided with a conductive circuit and is used to mechanically connect the first circuit area and the second circuit area; bending the second circuit area toward the first circuit area through the buffer area to form a bent state of the buffer area; and electrically connecting the second circuit area to the first circuit area through a conductive adhesive.

[0009] This ensures connection reliability while avoiding the bending stress and poor contact problems caused by the traditional reverse bending process. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0011] in: Figure 1 is a top view of the flexible substrate provided in an embodiment of the present technical solution; Figure 2 yes Figure 1 A cross-sectional view of a flexible substrate; Figure 3 is Figure 1 A cross-sectional view of a flexible substrate after a light-emitting diode is provided on the flexible substrate; Figure 4 yes Figure 3 A top view of the flexible substrate after light emitting diodes are set; Figure 5 yes Figure 3 A cross-sectional view of a light source module is formed after the flexible substrate is bent and electrically connected; Figure 6 yes Figure 5 A cross-sectional view of the light source module after the reinforcement plate is set; Figure 7 is a cross-sectional view of a copper-clad substrate provided by an embodiment of the present technical solution; Figure 8 is Figure 7 A cross-sectional view of a first circuit area, a buffer area, and a second circuit area formed on the substrate layer; Figure 9 is Figure 8 A cross-sectional view of a protective layer covering a copper foil layer; Figure 10 is Figure 9 A cross-sectional view of forming a plating layer on the copper foil layer; Figure 11 is Figure 10 A cross-sectional view showing a first opening and a second opening formed by the protective layer.

[0012] Description of main component symbols DETAILED DESCRIPTION The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0013] The method for manufacturing a light source module for a key core provided by the embodiment of the present technical solution includes the following steps: For the first step, see Figure 1 , providing a flexible substrate 11. The flexible substrate 11 includes a light emitting portion 111 and a connecting portion 112 extending from one side of the light emitting portion 111.

[0014] See also Figure 2 As shown, the connecting portion 112 includes, in order from the light-emitting portion 111 side, a first circuit region 113, a buffer region 114, and a second circuit region 115. The buffer region 114 is not provided with conductive circuits and serves to form a mechanical connection between the first circuit region 113 and the second circuit region 115. This design helps prevent the conductive circuits from breaking or fatigue failure during bending.

[0015] Furthermore, the first wiring region 113 may further include a first opening 113a for exposing the first pad 113b of the first wiring region 113. The second wiring region 115 may further include a second opening 115a disposed opposite the first opening 113a for exposing the second pad 115b of the second wiring region 115. In a preferred embodiment, the surfaces of the first pad 113b and the second pad 115b may not be covered with a solder mask, or may be subjected to a pre-treatment process such as surface roughening to enhance adhesion.

[0016] In one embodiment, the first wiring section 113, the buffer section 114, and the second wiring section 115 are integrally connected. When the buffer section 114 is not bent, the first wiring section 113 and the second wiring section 115 are disconnected. Specifically, the buffer section 114 isolates the first wiring section 113 from the second wiring section 115, and there is no electrical continuity between the first wiring section 113 and the second wiring section 115. This structural isolation enhances controllability and safety during subsequent electrical connections.

[0017] For the second step, see Figure 3 , a plurality of light emitting diodes 12 are arranged equidistantly in the light emitting portion 111 (such as Figure 4As shown). In this embodiment, the light-emitting diode (LED) 12 is a surface-mounted (SMD) structure, specifically 0603, 0805, or smaller sizes. It can be directly soldered to the circuit layer of the light-emitting portion 111 (not shown in the figure) to provide the illumination required for keyboard backlighting. Low-power, high-brightness, surface-mount LEDs are preferably used to meet the energy-saving and compact space requirements of the keyboard module. Each LED 12 can be fixed to a corresponding position on the surface of the flexible substrate 11 via solder paste soldering or reflow soldering and connected to the power supply and control signal terminals via pre-set wires. To ensure light source uniformity and visual consistency, the LEDs 12 are equidistantly arranged within the light-emitting portion 111 area. Their number and position can be optimized based on the keycap structure. Furthermore, the structure of this application can support multiple color LEDs, such as white, RGB, and single-color yellow / red, and can be combined with a control chip to enable dynamic backlight adjustment, such as brightness control, zone lighting, or key trigger response.

[0018] For the third step, please refer to Figure 5 , the second circuit area 115 is bent toward the first circuit area 113 through the buffer area 114, so that the buffer area 114 is in a bent state, and the second circuit area 115 is electrically connected to the first circuit area 113 via the conductive adhesive 13. In this embodiment, the first opening 113a is moved closer to the second opening 115a, so that the first pad 113b is electrically connected to the second pad 115b via the conductive adhesive 13. In one embodiment, the second circuit area 115 can be bent into a desired angle or direction based on actual needs, and then the second circuit area 115 and the first circuit area 113 are electrically connected through the conductive adhesive 13. In this application, the bending of the circuit in the bending area of ​​the circuit board in traditional manufacturing methods is eliminated, thereby ensuring connection reliability while avoiding the bending stress and poor contact problems caused by traditional structures. Specifically, because the electrical conductivity of the entire circuit of this application is established after bending, it is different from the traditional structure that is bent according to assembly needs after the electrical conductivity is established. Therefore, the structure of this application eliminates the need to bend interfaces or solder joints between dissimilar materials, thus avoiding the circuit breakage and stress concentration issues that occur with traditional FPC structures due to bending. This ensures the mechanical stability and electrical reliability of the flexible conductive path within the light source module. Furthermore, it mitigates the risk of failure caused by thermal expansion and contraction or long-term mechanical stress at interfaces or solder joints between dissimilar materials, thereby improving the module's service life and impact resistance.

[0019] In addition, if Figure 6As shown, to further enhance structural stability, the buffer zone 114 may be provided with a reinforcing plate 14. The reinforcing plate 14 may be made of a relatively rigid material such as sheet metal, PI board, or fiberglass board, and is bonded to the back of the buffer zone 114 with an adhesive, thereby enhancing the mechanical fatigue resistance of the bend. Specifically, when the buffer zone 114 is bent, the entire light source module 10 is assembled and electrically connected to external devices. To further enhance the structural rigidity of the buffer zone 114, the reinforcing plate 14 may be attached to the surface of the buffer zone 114 that requires support to enhance the structural strength of the bend.

[0020] At this point, the manufacture of the light source module 10 applied to the key core is completed.

[0021] See also Figure 6 The present application also provides a light source module 10 for a key core, comprising: a flexible substrate 11, comprising a light-emitting portion 111 and a connecting portion 112 extending from one side of the light-emitting portion 111; a plurality of light-emitting diodes 12, equidistantly arranged on the light-emitting portion 111; the connecting portion 112 sequentially comprises a first circuit area 113, a buffer area 114 and a second circuit area 115 from one side of the light-emitting portion 111; wherein the buffer area 114 is not provided with a conductive circuit, and the first circuit area 113 is mechanically connected to the second circuit area 115 through the buffer area 114; the first circuit area 113 and the second circuit area 115 are electrically connected via a conductive adhesive 13.

[0022] The first circuit area 113 has a first opening 113a for exposing the first pad 113b of the first circuit area 113, and the second circuit area 115 has a second opening 115a opposite to the first opening 113a for exposing the second pad 115b of the second circuit area 115. The buffer area 114 may have a reinforcing plate 14.

[0023] The light source module used in the key core of this application has the following advantages: This design effectively avoids the risk of conductive trace breakage in the bend area of ​​traditional FPCs, improving electrical connection reliability. It also achieves an integrated light source module structure, simplifying electrical connections and making it suitable for modular and standardized production. It is fully adaptable to automated processes, improving production line efficiency. The overall module is thin, making it suitable for ultra-thin keyboards, laptops, and consumer electronics devices. This application is not only applicable to standard keyboard structures but also has broad application potential in notebook computers, tablet input devices, industrial control equipment, and other input module scenarios requiring backlighting, demonstrating promising industrial application prospects.

[0024] In this example, see Figures 7 to 11 , and also provides a method for manufacturing a flexible substrate.

[0025] First, if Figure 7 As shown, a copper clad substrate 20 is provided, and the copper clad substrate 20 includes a base material layer 21 and a copper foil layer 22. Figure 8 As shown, the copper foil layer 22 is etched to form a first circuit area 221 , a buffer area 222 and a second circuit area 223 , wherein the first circuit area 221 and the second circuit area 223 are not connected by circuits.

[0026] Afterwards, if Figure 9 As shown, a protective layer 30 is formed on the copper foil layer 22 to partially cover and protect the first circuit area 221 and the second circuit area 223. Figure 10 As shown, a plating layer 40 is formed on the exposed second circuit area 223 , so that the second circuit area 223 covered with the plating layer 40 can be used as an external connection plug-in terminal for electrically connecting to an external device or mechanism.

[0027] Finally, if Figure 11 As shown, the protection layer 30 is formed with a first opening 31 and a second opening 32 , and the first opening 31 and the second opening 32 correspond to the first circuit area 221 and the second circuit area 223 respectively, thereby forming an exposed first pad 221 a and a second pad 223 a.

[0028] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A light source module for a key core, characterized by: include: A flexible substrate comprising a light emitting portion and a connecting portion extending from one side of the light emitting portion; A plurality of light emitting diodes are arranged at equal intervals on the light emitting portion; The connecting portion includes a first circuit area, a buffer area and a second circuit area in sequence from the light emitting portion side; The buffer zone is not provided with a conductive circuit, and the first circuit area is mechanically connected to the second circuit area via the buffer zone. When the buffer zone is not bent, the first circuit area and the second circuit area are in an open circuit state. The first circuit area and the second circuit area are isolated by the buffer zone, and no electrical conduction is established between the first circuit area and the second circuit area. The second circuit area is bent toward the first circuit area through the buffer area to make the buffer area present a bent state, and the second circuit area is electrically connected to the first circuit area through a conductive adhesive.

2. The light source module for a key core according to claim 1, wherein: The first circuit area is provided with a first opening for exposing a first pad in the first circuit area, and the second circuit area is provided with a second opening opposite to the first opening for exposing a second pad in the second circuit area.

3. The light source module for a key core according to claim 2, wherein: The first pad is electrically connected to the second pad through the conductive adhesive.

4. The light source module for a key core according to claim 1, wherein: The buffer zone is provided with a reinforcement plate.

5. The light source module for a key core according to claim 4, wherein: The reinforcement plate is made of metal sheet, PI board or glass fiber board.

6. A method for manufacturing a light source module for a key core, characterized in that: The method is used to manufacture the light source module for a key core according to any one of claims 1 to 5, and the method comprises: Providing a flexible substrate, comprising a light-emitting portion and a connecting portion extending from one side of the light-emitting portion; A plurality of light-emitting diodes are arranged equidistantly in the light-emitting portion, wherein the connecting portion includes, in order from one side of the light-emitting portion, a first circuit region, a buffer region, and a second circuit region, wherein the buffer region is not provided with a conductive circuit and is used to form a mechanical connection region between the first circuit region and the second circuit region; when the buffer region is not bent, the first circuit region and the second circuit region are in an open circuit state, the first circuit region and the second circuit region are isolated by the buffer region, and no electrical conduction is established between the first circuit region and the second circuit region; The second circuit area is bent toward the first circuit area through the buffer area to make the buffer area present a bent state, and the second circuit area is electrically connected to the first circuit area through a conductive adhesive.

7. The method for manufacturing a light source module for a key core according to claim 6, wherein: The first circuit area is formed with a first opening for exposing a first pad in the first circuit area, and the second circuit area is formed with a second opening opposite to the first opening for exposing a second pad in the second circuit area.

8. The method for manufacturing a light source module for a key core according to claim 7, wherein: The first pad is electrically connected to the second pad through the conductive adhesive.

9. The method for manufacturing a light source module for a key core according to claim 6, wherein: The buffer zone is provided with a reinforcement plate.

10. The method for manufacturing a light source module for a key core according to claim 6, wherein: The first circuit area, the buffer area, and the second circuit area are integrally connected. When the buffer area is not bent, the first circuit area and the second circuit area are in an open circuit state. The first circuit area and the second circuit area are isolated by the buffer area, and no electrical conduction is established between the two circuit areas.

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