Light source module applied to key cylinder and manufacturing method thereof

Abstract

The application relates to a connection structure of a flexible printed circuit, and discloses a light source module applied to a key core and a manufacturing method thereof. The light source module comprises a flexible substrate and a plurality of light emitting diodes. The connecting part of the flexible substrate is sequentially formed with a first circuit area, a buffer area and a second circuit area. 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 bending 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 electrically conductive relationship. The second circuit area is bent towards the first circuit area through the buffer area, so that the buffer area is in a bending state, and the second circuit area is electrically connected to the first circuit area through conductive glue. The application can avoid the fatigue problem caused by traditional reverse folding, improve the structural reliability and the module integration, and is suitable for thin keyboard products.

Description

TECHNICAL FIELD

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

[0002] With the development of electronic products towards light and thin, miniaturization and modularization, flexible printed circuit (FPC) is widely used in notebook computers, tablet computers, wearable devices and other products due to its good bendability, structural freedom and other characteristics, especially in the light source introduction structure of keyboard module, which plays a key role.

[0003] In the prior art, the keyboard backlight module adopts a "reverse folding structure" for conductive connection between the FPC and the lower layer circuit board, that is, the FPC is bent or turned over, so that the welding end forms an electrical connection with the mainboard or control board on the keyboard bottom plate. Although this structure can realize space conduction, it has the following technical problems:

[0004] The line of the bending part is prone to fatigue cracking: after long-term use of the reverse folding area, the bending stress is easily concentrated at the welding point or the line bending angle, resulting in cracking or virtual welding; high assembly complexity: the bending, positioning and welding process of the line require precise jigs, increasing the production process difficulty and cost; limited reliability: some reverse folding structures are prone to welding point lifting or unstable electrical properties under impact or thermal expansion and contraction conditions; limited structure packaging: the reverse folded line is difficult to be integrated with the overall keycap structure or thin film circuit, and it is difficult to meet the thinning or modular design requirements. In addition, some technologies currently use adhesive tape to fix the FPC wiring or use a reserved socket to conduct electricity, but such methods often require additional space, have poor stability, and are difficult to support mass automation processes.

[0005] Therefore, there is an urgent need for a new light source module structure and its manufacturing method, which can realize the effect of electrical conduction and mechanical connection without relying on the reverse folding structure, and improve the overall structural strength and production yield of the module. SUMMARY

[0006] The present application aims to overcome the problems of structural fatigue, complex assembly and unstable conduction of the backlight module of the keyboard caused by the reverse folding connection of the FPC in the prior art, and provides a light source module applied to key core and a manufacturing method thereof, which are structurally reliable, conductive and suitable for modular design.

[0007] The application provides a light source module applied to a key core, comprising: a flexible substrate having a light emitting part and a connecting part extending from one side of the light emitting part; a plurality of light emitting diodes equidistantly arranged on the light emitting part; the connecting part sequentially comprises a first circuit area, a buffer area and a second circuit area from one side of the light emitting part; wherein the buffer area is not provided with a conductive circuit and is used for providing a flexible mechanical connection function; the first circuit area forms a mechanical connection relationship with the second circuit area through the buffer area; when the buffer area is not in a bending 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 electrically conductive relationship; the second circuit area is bent towards the first circuit area direction through the buffer area, so that the buffer area is in a bending state, and the second circuit area is electrically connected to the first circuit area through conductive glue. Since the electrically conductive relationship of the overall circuit of the application is established after being bent, it is different from the traditional structure which is bent after the electrically conductive relationship is formed. Therefore, the structure of the application avoids the circuit breakage or stress concentration problem caused by the reverse bending of the traditional FPC structure (the interface between different materials or the welding point is usually a relatively weak part of the structure), thereby realizing the mechanical stability and electrical reliability of the flexible conductive path inside the light source module, reducing the welding points and plug-in structures, improving the automatic assembly rate, simplifying the overall production process. In addition, the failure risk caused by thermal expansion and contraction or long-term mechanical stress of the interface between different materials or the welding point can be alleviated, and the service life and impact resistance of the module are improved.

[0008] Preferably, the first circuit area and the second circuit area are respectively provided with openings to expose the solder pads, and the conductive glue is connected to the corresponding solder pads through the openings, thereby realizing electrical conduction. Therefore, the defect of poor reliability after the circuit is bent in the traditional structure can be solved. In addition, the buffer area can also be provided with a reinforcing plate to further improve the structural strength.

[0009] The application also provides a manufacturing method of a light source module applied to a key core, which is used for manufacturing the light source module applied to the key core and comprises the following steps: providing a flexible substrate having a light emitting part and a connecting part extending from one side of the light emitting part, wherein the connecting part comprises a first circuit area, a buffer area and a second circuit area; arranging a plurality of light emitting diodes equidistantly on the light emitting part; the buffer area is not provided with a conductive circuit and is used for mechanically connecting the first circuit area and the second circuit area; bending the second circuit area towards the first circuit area direction through the buffer area, so that the buffer area forms a bending state; and electrically connecting the second circuit area to the first circuit area through conductive glue.

[0010] The bending stress and poor contact problem caused by the traditional reverse bending process can be avoided while ensuring reliable connection. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description only only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0012] Among them:

[0013] Figure 1 is the top view of the flexible substrate provided by the technical solution embodiment;

[0014] Figure 2 is the cross-sectional view of the flexible substrate of Figure 1 ;

[0015] Figure 3 is the cross-sectional view of the flexible substrate of Figure 1 after setting the light emitting diode on it;

[0016] Figure 4 is the top view of the flexible substrate of Figure 3 after setting the light emitting diode on it;

[0017] Figure 5 is the cross-sectional view of the light source module of Figure 3 after the flexible substrate is bent and electrically connected to form the light source module;

[0018] Figure 6 is the cross-sectional view of the light source module of Figure 5 after setting the reinforcing plate on it;

[0019] Figure 7 is the cross-sectional view of the copper-clad substrate provided by the technical solution embodiment;

[0020] Figure 8 is the cross-sectional view of the first line area, the buffer area and the second line area formed on the substrate layer in Figure 7 ;

[0021] Figure 9 is the cross-sectional view of the protective layer covering the copper foil layer in Figure 8 ;

[0022] Figure 10 is the cross-sectional view of the plating layer formed on the copper foil layer in Figure 9 ;

[0023] Figure 11 is the cross-sectional view of the protective layer forming the first opening and the second opening in Figure 10 .

[0024] Main element symbol explanation

[0025] Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] The method for manufacturing a light source module for a key core provided in this embodiment of the technical solution includes the following steps:

[0028] First step, please refer to Figure 1 A flexible substrate 11 is provided. 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.

[0029] Please see again Figure 2 As shown, the connecting portion 112 sequentially includes a first circuit area 113, a buffer zone 114, and a second circuit area 115 from one side of the light-emitting portion 111. The buffer zone 114 is not provided with conductive lines and is used to form a mechanical connection area between the first circuit area 113 and the second circuit area 115. This design helps to avoid the problem of conductive lines breaking or fatigue failure during bending.

[0030] Furthermore, the first circuit region 113 may also have a first opening 113a to expose the first solder pad 113b of the first circuit region 113, and the second circuit region 115 may also have a second opening 115a opposite to the first opening 113a to expose the second solder pad 115b of the second circuit region 115. In a preferred embodiment, the surfaces of the first solder pad 113b and the second solder pad 115b may not be covered with a solder resist layer, or the adhesion performance may be enhanced by pretreatment processes such as surface roughening.

[0031] In one embodiment, the first line area 113, the buffer zone 114, and the second line area 115 are integrally connected. When the buffer zone 114 is not bent, the first line area 113 and the second line area 115 are in an open circuit state. Specifically, the first line area 113 and the second line area 115 are isolated by the buffer zone 114, and no electrical connection is established between them. Structurally, this isolation makes subsequent electrical connections more controllable and safer.

[0032] Step 2, please refer toFigure 3 A plurality of light emitting diodes 12 are arranged equidistantly in the light emitting portion 111 (as shown in Figure 4 In this embodiment, the light emitting diodes 12 are of a patch type structure, and can be of a 0603, 0805 or smaller size, and can be directly soldered to the circuit layer (not shown in the figure) of the light emitting portion 111 to provide the required illumination function for the keyboard backlight. Preferably, low-power, high-brightness, surface-mounted LEDs are used to meet the energy saving and compact space requirements of the keyboard module. Each light emitting diode 12 can be fixed to the corresponding position on the surface of the flexible substrate 11 by means of soldering with tin paste or reflow soldering, and is connected to the power supply and control signal end through a predetermined lead. In order to ensure the uniformity of the light source and the visual consistency, the light emitting diodes 12 are arranged equidistantly in the light emitting portion 111, and the number and position can be optimized according to the structure of the keycap. In addition, the structure of the present application can also support LEDs of various colors, such as white light, RGB, single-color yellow / red light, etc., and can be combined with a control chip to dynamically adjust the backlight, such as brightness control, regional lighting or key trigger response, etc.

[0033] Thirdly, referring to Figure 5 The second circuit area 115 is bent towards 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 through the conductive adhesive 13. In this embodiment, the first opening 113a is moved towards the second opening 115a, so that the first solder pad 113b is electrically connected to the second solder pad 115b through the conductive adhesive 13. In an embodiment, the second circuit area 115 can be bent to the required angle or direction according to actual needs, and the second circuit area 115 and the first circuit area 113 are then electrically connected through the conductive adhesive 13. In the present application, the circuit in the bending area of the traditional circuit board is avoided, so that the connection reliability is ensured, and the problems of bending stress and poor contact caused by the traditional structure are avoided. In detail, the electrical connection of the overall circuit in the present application is established after bending, which is different from the traditional structure in which the electrical connection is established first and then bent according to the assembly needs. Therefore, the structure of the present application does not need to bend the interface or the solder joint of different materials, so that the problems of circuit rupture or stress concentration caused by bending in the traditional FPC structure are avoided, and the mechanical stability and electrical reliability of the flexible conduction path in the light source module are realized. In addition, the failure risk caused by thermal expansion and contraction or long-term mechanical stress of the interface or solder joint of different materials is also alleviated, and the service life and impact resistance of the module are improved.

[0034] In addition, asFigure 6 To further strengthen the stability of the structure, the buffer area 114 can be provided with a reinforcing plate 14, wherein the material of the reinforcing plate 14 can be selected from metal sheets, PI plates, glass fiber plates and other materials with certain rigidity, and is bonded to the back of the buffer area 114 by an adhesive, thereby improving the mechanical fatigue resistance of the bending part. Specifically, when the buffer area 114 is in a bent state, the overall light source module 10 has completed the overall assembly and establishes an electrical connection relationship with the external device. In order to further strengthen the structural rigidity of the buffer area 114, the reinforcing plate 14 can be attached to the surface of the buffer area 114 that needs to provide support function, so as to improve the structural strength of the bending part.

[0035] At this point, the production of the light source module 10 applied to the key core is completed.

[0036] Please refer to Figure 6 The application also provides a light source module 10 applied to a key core, comprising: a flexible substrate 11, including a light emitting part 111 and a connecting part 112 extending from one side of the light emitting part 111; a plurality of light emitting diodes 12 arranged equidistantly on the light emitting part 111; the connecting part 112 sequentially includes a first circuit area 113, a buffer area 114 and a second circuit area 115 from one side of the light emitting part 111; wherein the buffer area 114 is not provided with a conductive circuit, the first circuit area 113 is mechanically connected with the second circuit area 115 through the buffer area 114; the first circuit area 113 and the second circuit area 115 are electrically connected through a conductive adhesive 13.

[0037] The first circuit area 113 is provided with a first opening 113a for exposing a first solder pad 113b of the first circuit area 113, and the second circuit area 115 is provided with a second opening 115a arranged opposite to the first opening 113a for exposing a second solder pad 115b of the second circuit area 115. The buffer area 114 can be provided with a reinforcing plate 14.

[0038] The light source module applied to the key core has the following advantages:

[0039] The application effectively avoids the risk of fracture of the conductive circuit in the bending area of the traditional FPC, improves the electrical connection reliability, realizes the integrated light source module structure, simplifies the electrical connection, is suitable for modularization and standardized production, can completely adapt to the automatic process, improves the production line efficiency, and has small overall module thickness, which is suitable for ultra-thin keyboards, laptops and consumer electronic devices. The application is not only suitable for standard keyboard structures, but also can be extended to notebook computers, tablet input devices, industrial control devices and other input module scenes that need backlight function, and has good industrial application prospect.

[0040] In this embodiment, please refer to Figures 7 to 11A flexible substrate manufacturing method is also provided.

[0041] First, as shown in FIG. 1, a copper-clad substrate 20 is provided, which includes a substrate layer 21 and a copper foil layer 22. As shown in FIG. 2, the copper foil layer 22 is etched so that the copper foil layer 22 is formed into 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 in circuit communication. Figure 7 Figure 8 As shown in FIG. 3, 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.

[0042] As shown in FIG. 4, 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 a plug-in end for external connection to electrically connect to external devices or mechanisms. Figure 9 Figure 10 As shown in FIG. 5, the protective 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 exposed first and second solder pads 221a and 223a.

[0043] As shown in FIG. 6, the protective 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 exposed first and second solder pads 221a and 223a. Figure 11

[0044] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.​​​

Claims

1. A light source module applied to a key core, characterized in that: include: A flexible substrate includes a light-emitting portion and a connecting portion extending from one side of the light-emitting portion; Multiple light-emitting diodes are arranged at equal intervals in the light-emitting part; The connecting portion includes, sequentially from one side of the light-emitting portion, a first circuit area, a buffer area, and a second circuit area; Wherein, the buffer zone is not provided with conductive lines, the first line area is mechanically connected to the second line area through the buffer zone, when the buffer zone is not in a bent state, the first line area and the second line area are in an open circuit state, the first line area and the second line area are isolated by the buffer zone, and the first line area and the second line area are not electrically connected. The second line area is bent toward the first line area via the buffer zone, so that the buffer zone is in a bent state, and the second line area is electrically connected to the first line area through conductive adhesive.

2. The light source module applied to the key core as described in claim 1, characterized in that: The first circuit area has a first opening to expose the first solder pad of the first circuit area, and the second circuit area has a second opening opposite to the first opening to expose the second solder pad of the second circuit area.

3. The light source module applied to the key core as described in claim 2, characterized in that: The first solder pad is electrically connected to the second solder pad via the conductive adhesive.

4. The light source module applied to the key core as described in claim 1, characterized in that: The buffer zone is equipped with a reinforcing plate.

5. The light source module applied to the key core as described in claim 4, characterized in that: The reinforcing plate is made of metal sheet, PI board or fiberglass board.

6. A method for manufacturing a light source module applied to a key core, characterized in that: The method is used to manufacture a light source module applied to a key core as described in any one of claims 1 to 5, the method comprising: A flexible substrate is provided, including a light-emitting portion and a connecting portion extending from one side of the light-emitting portion; Multiple light-emitting diodes are arranged equidistantly on the light-emitting part. The connecting part includes, from one side of the light-emitting part, a first circuit area, a buffer area, and a second circuit area. The buffer area is not provided with conductive lines and is used to form a mechanical connection area between the first circuit area and the second circuit area. 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 connection is established between the first circuit area and the second circuit area. The second line area is bent toward the first line area via the buffer zone, so that the buffer zone is in a bent state, and the second line area is electrically connected to the first line area through conductive adhesive.

7. The method for manufacturing a light source module applied to a key core as described in claim 6, characterized in that: The first circuit area has a first opening to expose a first solder pad of the first circuit area, and the second circuit area has a second opening opposite to the first opening to expose a second solder pad of the second circuit area.

8. The method for manufacturing a light source module applied to a key core as described in claim 7, characterized in that: The first solder pad is electrically connected to the second solder pad via the conductive adhesive.

9. The method for manufacturing a light source module applied to a key core as described in claim 6, characterized in that: The buffer zone is equipped with a reinforcing plate.

10. The method for manufacturing a light source module applied to a key core as described in claim 6, characterized in that: The first line area, the buffer zone, and the second line area are connected as a whole. When the buffer zone is not bent, the first line area and the second line area are in an open circuit state. The first line area and the second line area are isolated by the buffer zone, and the two line areas do not establish an electrical connection.

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