Electric and mechanical connection method for at least two flexible wiring boards or wiring board segments

Abstract

To provide an electric and mechanical connection method for at least two flexible wiring boards or wiring board segments.SOLUTION: Respective wiring boards or wiring board segments include bottom part insulation layers, preferably, electric conductive structures as electric conductor wires, and upper insulation layers. An upper insulation layer is exposed or removed at a specific part in a connection region to have a contact surface. A reinforcing / positioning layer is used to achieve accurate positioning using a position mark, and a lamination connection process step is performed to make safe and flexible connections.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to insulation displacement conductive processes, and more particularly to methods for electrically and mechanically connecting at least two flexible wiring boards or wiring board segments. [Background technology]

[0002] Generally, flexible wiring boards are connected components within a circuit, but by integrating additional active and / or passive electronic components, they can also form independent circuits.

[0003] The advantage of flexible printed circuit boards is that their non-rigid design and thin thickness allow them to bend, roll, fold, and attach almost freely in the Z-axis direction. This allows them to be fitted into housing structures and allow electrical connections to be made in the same way as conductors. Another advantage of flexible printed circuit boards is their light weight. This has made them popular in highly integrated modules for mobile electronics, communications equipment, PC peripherals, and other applications in automotive technology and aerospace.

[0004] Furthermore, the flexibility of the wiring board makes assembly easier, particularly by adjusting for the mounting tolerances of the equipment.

[0005] A flexible wiring board primarily comprises a base layer of insulating carrier material, one or more electrical conductors, and a covering layer also made of insulating material.

[0006] The layers are firmly bonded together by a lamination process.

[0007] The ends of the electrical conductors are exposed through openings in the base layer and / or cover layer for contacting and establishing the necessary electrical contact with other electrical or electronic modules, which can be achieved by welding, conductive adhesive, crimping, or crimping connections.

[0008] The manufacturing of flexible printed circuit boards is usually based on two different technologies.

[0009] One such technique is known as "flex lamination," in which individual conductors are arranged in a bent configuration and, if necessary, are fitted together to stack multiple individual flexible wiring boards at once.

[0010] The individual wiring boards or wiring board segments are then separated by cutting with a cutting blade or laser light.

[0011] In this method, the available area of ​​the laminator becomes a limiting factor in the length x and width y of the flexible wiring board.

[0012] Laminator space is limited, so larger circuit board sizes require the use of specialized equipment at correspondingly higher costs.

[0013] In addition, so-called "roll-to-roll lamination" is also known.

[0014] In this method, flexible wiring boards can be manufactured on a continuous reel shaft or by dividing the lamination into sections. This allows for the manufacture of flexible wiring boards with a longer length x. However, the width of the reel shaft is generally limited to 250 to 500 mm, so the limiting factor in this method is the width y.

[0015] The electrical and mechanical connection of individual segments, for example to connect individual circuit boards to each other or to realize corner structures in flexible circuit boards, is part of the technical field. Such connections can be realized by conductive adhesives. To protect the connections made by conductive adhesives, the connection areas are usually protected by a rigid element, for example in the form of a plastic encapsulation.

[0016] Patent document 1 discloses a multilayer structure that allows electrical contact between a flexible substrate film and a conductive structure (e.g., a flexible wiring board). In this solution, the actual substrate film may be thermoformed and covered with a plastic layer. Electrical contact is achieved by contact elements that are introduced through openings in the substrate film.

[0017] Patent Document 2 discloses a flat cable connection system, in which a connection box is used to fix the end of the flat cable to be connected.

[0018] The contact connection method for flexible wiring boards described in Patent Document 3 uses a non-conductive adhesive, a conductive adhesive, or solder. In particular, an adhesive method is used to achieve safe electrical contact.

[0019] In connection processes for flexible wiring boards using additive materials similar to those described in Patent Document 4, the flexibility of the connection points is lost, limiting or even making impossible the advantages of flexible wiring boards in the above-mentioned applications. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] European Patent No. 3610707 [Patent Document 2] European Patent No. 3331114 [Patent Document 3] European Patent No. 2440024 [Patent Document 4] International Patent Application Publication No. 2010 / 140469 Summary of the Invention [Problem to be solved by the invention]

[0021] The present invention relates to a method for electrically and mechanically connecting at least two flexible wiring boards or wiring board segments, each of which consists of a bottom insulating layer, an electrically conductive structure, in particular a conductor, and a top insulating layer. According to the general concept of claim 1, the top insulating layer is exposed or removed in part of the connection area to provide a contact surface, and according to the features of claim 13, flexible wiring boards of any length can be obtained. [Means for solving the problem]

[0022] The problem of the present invention is solved by a flexible wiring board of any length and a predetermined width, which is produced by the method of claim 1 and the combination of the features of claim 13. The dependent claims contain at least one suitable design and improvement.

[0023] This method assumes that there is an electrical and mechanical connection between at least two flexible wiring boards or wiring board segments.

[0024] Each of these wiring boards or wiring board segments consists of a bottom insulating layer, a conductive structure (including in particular conductor tracks), and a top insulating layer.

[0025] In the area of ​​the actual electrical connection, the upper insulating layer is exposed or removed to ensure an accessible contact surface. The material of the conductor tracks can be copper, aluminum or a corresponding alloy. A preferred material for the conductor tracks is a copper material with corresponding toughness.

[0026] According to the present invention, a first reinforcing and positioning layer is provided on a first flexible wiring board having an exposed contact surface, and a second reinforcing and positioning layer is provided on a second flexible wiring board having an exposed contact surface.

[0027] The surfaces of the first reinforcing and positioning layer and the second reinforcing and positioning layer extend beyond their respective contact surfaces to form a connection region.

[0028] To ensure the accuracy of the position, the reinforcing and positioning layer is provided with positioning marks, and preferably with positioning holes.

[0029] A thermally active layer or film is then coated or placed within the connection area while retaining the contact surface area.

[0030] Once the wiring boards and their contact surfaces have been accurately positioned, the lamination and connection step is carried out.

[0031] Lamination is usually performed using a combination of pressure and temperature. For proper processing, the lateral overhangs of the reinforcing and positioning layers can be removed.

[0032] In one embodiment of the present invention, the thermally active layer or film has alignment marks, in particular alignment holes, and recesses in the areas corresponding to the exposed contact surfaces, which ensure that the opposing contact surfaces come into direct contact with each other during the lamination process, thereby forming a low-resistance contact connection.

[0033] The tolerance range for the positional accuracy of the thermally active layer or film and the reinforcing and positioning layer is 0.2~0.5mm (maximum).

[0034] The diameter of the positioning hole is 0.5 to 5.0 mm, preferably 0.5 to 1.5 mm.

[0035] Furthermore, the positioning holes can also be used to ensure ventilation of the connection area during the lamination process, making the structure in the connection area as flat and void-free as possible.

[0036] In order to maintain the necessary flexibility in the connection area, both the reinforcing and positioning layer and the thermally active layer or film are made of a flexible, non-rigid material, the thickness of which in the connection area is slightly greater than the thickness of the adjacent flexible conductor tracks or material, for example 100-400 μm.

[0037] The positioning marks or positioning holes on the reinforcing and positioning layer are composed of a first group and a second group.

[0038] The spacing of the first group corresponds on the one hand to the size of the contact surface and on the other hand to the width of the flexible wiring board to be connected.

[0039] The second group is located inside the area occupied by the flexible wiring board, but can also be located outside. If the conductor tracks are widely spaced on each wiring board and there is corresponding free space, the positioning holes can also be located inside the wiring board.

[0040] The reinforcing and positioning layer is preferably made of a thermosetting material and may be provided with an adhesive coating.

[0041] The thermally active layer or film is preferably made of an epoxy resin material.

[0042] The angle of the connected wiring boards or wiring board segments is 0° to 180°, and preferably 90° to 180°.

[0043] According to the present invention, the flexible wiring board has an arbitrary length and a predetermined width, and includes at least 2 to n wiring board segments and at least one stacking connection device for electrical and mechanical coupling.

[0044] The connection device has exposed electrical contact surfaces that are in direct contact with each other, and further has at least one reinforcing and positioning layer on each of the top and bottom.

[0045] In another embodiment of the invention, the stacked connection device has an additional layer of heat-activated material, preferably epoxy resin, on the outside and around the contact surface, which layer of heat-activated material also serves as a height compensation and prevents the appearance of unnecessary steps in the area of ​​the connection device.

[0046] The advantage of the present invention over the prior art is that it provides a more advanced method for forming an electrical and mechanical connection between at least two flexible wiring boards. This method allows for free selection of length and width dimensions, i.e., free selection of dimensions within a plane. Furthermore, it is possible to utilize existing laminators for conventional lamination processes. Another objective of the present invention is to maintain flexibility, particularly at the connection points, i.e., the connection regions, to the same degree of flexibility as the wiring boards themselves. Therefore, the connection regions should not be rigid, but flexible, and should have a small thickness or height. [Brief explanation of the drawings]

[0047] In order to clearly explain the technical idea of ​​the embodiments of the present application, the drawings used in the embodiments are briefly described below. The drawings are only a part of the embodiments of the present application, and it is obvious that a person skilled in the art can obtain other drawings based on these drawings without requiring creative acts.

[0048] [Figure 1] FIG. 2 is a longitudinal cross-sectional view of a connection area of ​​two wiring boards. [Figure 2] 1 is a flow chart of an exemplary process for manufacturing a connection device. [Figure 3] 1 is a schematic diagram of a thermally active layer or film coated or applied to the connection area. [Figure 4] Basic diagram of the reinforcing and positioning layer with positioning holes. [Figure 5] FIG. 1 is a plan view of two connection circuit board segments with connection areas linearly positioned at 180°. [Figure 6] 6 is a schematic diagram similar to that shown in FIG. 5, but with connected circuit board segments at a 90° angle. DETAILED DESCRIPTION OF THE INVENTION

[0049] Hereinafter, embodiments of the present application will be described in detail with reference to the drawings.

[0050] The following describes embodiments of the present application through specific examples. Those skilled in the art will easily understand other advantages and effects of the present application from the contents disclosed herein. It is clear that the described embodiments are only a portion of the embodiments of the present application, and are not all of the embodiments. The present application can also be implemented or applied in other different specific embodiments. Each detail in this specification can be modified or altered in various ways based on different perspectives and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other, if no problem occurs. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present application without requiring creative acts are within the scope of protection of the present application.

[0051] Various aspects of embodiments within the scope of the claims of this application are described below. The aspects described herein may be implemented in a wide variety of forms. Specific structures and / or functions described herein are merely exemplary. Based on this application, one skilled in the art should understand that an aspect described herein can be implemented independently of any other aspect, and that two or more of these aspects can be combined in various ways. For example, the device and / or method may be implemented using any number and aspects described herein. Alternatively, the device and / or method may be implemented and / or performed using other structure and / or functionality in addition to one or more aspects described herein.

[0052] It should be noted that the drawings shown in the following embodiments merely provide a rough explanation of the basic concept of the present application. The drawings only show components relevant to the present application and are not based on the number, shape, and size of the components in actual implementation. In actual implementation, the type, quantity, and ratio of each component may be changed arbitrarily, and the arrangement of the components may also become more complex.

[0053] Furthermore, in the following description, specific details are provided to facilitate an understanding of the embodiments. However, it will be understood by one skilled in the art that the aspects may be practiced without these specific details.

[0054] In the arrangement method shown in FIG. 1, a wiring board consisting of two wiring board segments 1 and 2 is formed.

[0055] The wiring board segments 1 and 2 are connected by laminating the joints formed therebetween.

[0056] The first flexible wiring board segment 1 consists of a bottom insulating layer 103 , a first conductive structure 102 consisting of a number of conductor tracks, and a top insulating layer 101 .

[0057] Second flexible wiring board segment 2 is composed of second bottom insulating layer 104, second conductive structure 105, and second top insulating layer .

[0058] The first flexible wiring board segment 1 and the second flexible wiring board segment 2 have exposed areas of the first upper insulating layer 101 and the second upper insulating layer 106, respectively, and have first contact surfaces 121 and second contact surfaces 122 formed thereon.

[0059] These contact surfaces are directly opposed, providing a low resistance electrical contact.

[0060] A first reinforcing and positioning layer 111 is coated on the first bottom insulating layer 103, and a second reinforcing and positioning layer 113 is coated on the second bottom insulating layer 104. Positioning holes are provided in both the two reinforcing and positioning layers 111 and 113, so that the contact surfaces 121 and 122 are aligned.

[0061] In this regard, reference is made to the reinforcing and positioning layers 111 and 113 .

[0062] A conventional sandwich connection is achieved by laminating the first flexible wiring board segment 1 and the second flexible wiring board segment 2 together. This is achieved by introducing or coating a sol layer (thermally activated layer or film) 112 of a heat-activated adhesive around the first contact surface 121 and the second contact surface 122. The sol layer 112 can also be a heat-activated layer or film.

[0063] Typically, the insulating base layer and top insulating layer are constructed from a heat resistant plastic film, preferably a polyimide film.

[0064] The sol layer 112 may be a heat activated adhesive, preferably an epoxy resin material.

[0065] Alternatively, the sol layer 112 may be a heat-resistant plastic film and may be disposed between the first flexible wiring board segment 1 and the second flexible wiring board segment 2 .

[0066] The method of the present invention is described below with reference to the procedure in FIG.

[0067] Here, it is assumed that wiring board 2 includes bottom insulating layer 104, first conductive structure 105, and top insulating layer 106. Similarly, first wiring board segment 1 includes first bottom insulating layer 103, first conductive structure 102, and first top insulating layer 101. In the areas of first top insulating layer 101 or second top insulating layer 106, exposure is performed to obtain first contact surface 121 and second contact surface 122 (see also FIG. 1 ).

[0068] Next, first wiring board segment 1 and first reinforcing and positioning layer 111 are permanently connected by lamination or adhesive, and second wiring board segment 2 and second reinforcing and positioning layer 113 are permanently connected by lamination or adhesive.

[0069] Next, the connection area of ​​the first wiring board segment 1 is coated with the sol layer 112, surrounding the first contact surface 121 but leaving one side of the surface exposed. Next, the second contact surface 122 of the second wiring board 2 is placed on the first contact surface 121, and they are laminated and connected at the connection area by appropriate pressure and temperature treatment.

[0070] The protruding parts of the reinforcing and positioning layer (see FIGS. 5 and 6) beyond the contours of the circuit board segments can then be removed, for example by cutting them off.

[0071] 3 shows the shape of the thin film structure sol layer 112 having a recess 301. The recess 301 corresponds to the shape and position of the contact surface 121 or 122. The sol layer 112 further has a positioning hole 302, which allows positioning relative to the reinforcing and positioning layers 111, 113 having similar positioning holes 401 (see FIG. 4).

[0072] The reinforcing and positioning layers 111 and 113 each have a set of outer positioning holes 401 and a set of inner positioning holes 402 .

[0073] 5 or 6, the inner positioning holes 402 are used to position the flexible wiring board strips to be connected, and the outer positioning holes 401 are aligned with the positioning holes 302 of the thermally active layer or film 112.

[0074] The method of the present invention makes it possible to produce flexible wiring boards of very large lengths and widths, exceeding the lamination range of conventional laminators, while the connection area itself remains highly flexible, with the overall thickness of the material being only slightly greater than the thickness of the wiring board portion.

[0075] Therefore, flexible wiring boards with such designed connection areas can be very easily realized for various applications, such as embedding in multi-layer safety glass, in particular for use in single-film safety glass in the automotive technology field.

[0076] The above are merely examples of specific embodiments of the present application, and the scope of protection of the present application is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application shall be included in the scope of protection of the present application. Therefore, the scope of protection of the present application shall be based on the scope of protection of the claims.

Claims

1. A method for electrically and mechanically connecting at least two flexible wiring boards or wiring board segments, each wiring board or wiring board segment comprising a bottom insulating layer (103, 104), an electrically conductive structure (102, 105), and a top insulating layer (101, 106), wherein a portion of a connection area of ​​the top insulating layer is exposed or removed to provide a contact surface (121, 122), the method comprising: A first reinforcing and positioning layer (111) is coated on the exposed contact surface (121) of the first flexible wiring board (1); a second reinforcing and positioning layer (113) is coated on the exposed contact surface (122) of the second flexible wiring board (2); the surfaces of the first reinforcing and positioning layer (111) and the second reinforcing and positioning layer (113) extend beyond the contact surfaces (121, 122), respectively, to form connection regions; forming positioning marks on the first reinforcing and positioning layer (111) and the second reinforcing and positioning layer (113) to ensure accurate positioning; While maintaining the contact surfaces (121, 122), coating or placing a thermally active layer or film (112) within the connection area; After accurate positioning of the first flexible wiring board (1) and the second flexible wiring board (2) with the contact surfaces (121, 122) is completed, a lamination process step is performed.

2. 2. The method of claim 1, further comprising removing lateral protruding portions of the first reinforcing and positioning layer (111) and the second reinforcing and positioning layer (113).

3. The method of claim 1 or 2, wherein the lamination process step comprises a pressure and temperature treatment.

4. The method according to any one of claims 1 to 3, wherein the thermally active layer or film (112) has positioning marks and recesses (301) which are positioning holes (302) in areas corresponding to the exposed contact surfaces (121, 122).

5. 5. The method according to claim 1, wherein the tolerance range of the positional accuracy of the thermally active layer or film (112) and the first and second reinforcing and positioning layers (111, 113) is 0.2 to 0.5 mm.

6. The method according to any one of claims 1 to 5, wherein the diameter of the positioning hole (302) is between 0.5 and 5.0 mm, preferably between 0.5 and 1.5 mm.

7. 7. The method of claim 6, wherein the connection area is vented through the locating holes (302) during the lamination step.

8. 8. The method according to any one of claims 1 to 7, wherein the first reinforcement and positioning layer (111), the second reinforcement and positioning layer (113), and the thermally active layer or film (112) are all made of flexible and non-rigid materials to maintain flexibility in the connection area.

9. In the first reinforcing and positioning layer (111) and the second reinforcing and positioning layer (113), the positioning marks are divided into a first group (402) and a second group (401); The first group (402) is spaced apart to match the size of the contact surface and the width of the flexible wiring board (1, 2) to be connected; The method according to any one of claims 1 to 8, wherein the second group (401) is arranged inside or outside an area of ​​the flexible wiring board (1, 2).

10. The method according to any one of the preceding claims, wherein the first reinforcing and positioning layer (111) and the second reinforcing and positioning layer (113) consist of a thermosetting material.

11. The method of any one of claims 1 to 10, wherein the thermally active layer or film (112) comprises an epoxy resin material.

12. The method according to any one of claims 1 to 11, wherein the angle of the flexible wiring boards or flexible wiring board segments to be connected is between 0° and 180°, preferably between 90° and 180°.

13. The flexible wiring board has an arbitrary length and a predetermined width, and includes at least two wiring board segments (1, 2) and at least one stacking connection device for electrical and mechanical connection; The method according to any one of claims 1 to 12, wherein the stack connection device has opposing exposed contact surfaces (121, 122) and has at least one upper reinforcement and positioning layer (111) and a lower reinforcement and positioning layer (113).

14. 14. The flexible wiring board according to claim 13, wherein the stacked connection device comprises an additional layer of heat-active material (112), preferably epoxy resin, around the periphery of the contact surfaces (121, 122).

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