Sealed structure with flexible printed wiring board and manufacturing method thereof

Abstract

To provide a sealed structure with a flexible printed wiring board and a manufacturing method thereof, which can obtain sufficient sealing performance with a simple structure.SOLUTION: A case includes a pair of flexible thin plate portions 220 that fit along an opening O and face both sides of an FPC 100, and an adhesive layer 230F is provided in advance on the inner surfaces of the pair of thin plate portions 220. With the FPC 100 in place, gaps are sealed by adhesion using the adhesive layers 230F provided on the inner surfaces of the pair of thin plate portions 220.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a sealed structure having a flexible printed wiring board and a method for manufacturing the same. [Background technology]

[0002] In various electronic devices, flexible printed circuit boards (hereinafter referred to as FPCs) are widely used to electrically connect multiple electronic components installed inside the case to a power source or external devices outside the case. The FPC is used with a part of it pulled out from inside the case through an opening in the case. As a result, one end of the multiple wirings installed on the FPC is connected to multiple electronic components inside the case, and the other end of the multiple wirings is connected to a power source or various devices outside the case.

[0003] In such electronic devices, a seal is sometimes provided to close the gap between the opening of the case and the FPC in order to prevent water, dust, etc. from entering the case. For example, a sealed structure is provided by integrally providing an elastic grommet made of rubber or the like with the FPC (see Patent Document 1) or by filling the gap with liquid rubber.

[0004] However, in the case of a structure with a grommet, it is necessary to increase the rigidity of the case and to increase the thickness of the case in order to fit the grommet. Also, in the case of a structure in which liquid rubber is filled into the gap, a structure that allows the liquid rubber to be filled (for example, a groove in the case) is required, and the manufacturing process becomes complicated, making it difficult to control costs. As described above, there is still room for improvement. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5354281 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a sealed structure having a flexible printed wiring board that can obtain sufficient sealing performance with a simple structure, and a method for manufacturing the same. [Means for solving the problem]

[0007] The present invention employs the following means to solve the above problems.

[0008] The sealing structure of the present invention comprises: A sealing structure for sealing a gap between an inner wall surface of an opening provided in a case and a flexible printed wiring board that is used in a state where a part of the flexible printed wiring board is pulled out from inside the case through the opening, the case includes a pair of flexible thin plate portions that are aligned with the opening and that face both sides of the flexible printed wiring board, An adhesive layer is provided in advance on the inner surfaces of the pair of thin plate portions, and when the flexible printed wiring board is placed, the gap is sealed by adhesion using the adhesive layer provided on the inner surfaces of the pair of thin plate portions, respectively.

[0009] According to the present invention, a sealed structure can be obtained simply by providing a pair of thin plate parts on the case and providing an adhesive layer on the inside of the pair of thin plate parts. Also, the flexible printed wiring board can be sealed by being sandwiched between the pair of thin plate parts. Therefore, the flexible printed wiring board can be sealed by being sandwiched between the pair of thin plate parts. Since the adhesive layer is provided in the narrow gap between the plate and the thin plate, the space required is small, and the sealing performance is improved accordingly.

[0010] The flexible printed wiring board is A base film; Wiring provided on the base film; a cover film attached to the base film so as to cover the wiring; Equipped with It is preferable that the base film and the cover film have different widths in the short side direction at least in the region where adhesion is performed by the adhesive layer.

[0011] This forms a step on the side of the flexible printed wiring board, thereby preventing the occurrence of areas on the side of the flexible printed wiring board that are not filled with the adhesive layer near the center of the thickness direction of the flexible printed wiring board.

[0012] The wiring and the cover film may be provided on both sides of the base film.

[0013] Before bonding with the adhesive layer, supplemental adhesive layers may be provided in advance on both sides of the flexible printed wiring board so as to protrude on both sides in the short side direction of the flexible printed wiring board.

[0014] In this way, by providing a supplementary adhesive layer, it is possible to prevent the occurrence of areas on the side of the flexible printed wiring board near the center in the thickness direction of the flexible printed wiring board where the adhesive layer is not filled.

[0015] The method for manufacturing the sealing structure of the present invention includes the steps of: 1. A method for manufacturing a sealing structure for sealing a gap between an inner wall surface of an opening provided in a case and a flexible printed wiring board that is used in a state where a part of the flexible printed wiring board is pulled out from inside the case through the opening, comprising: providing a pair of flexible thin plate portions on the case so as to be aligned with the opening and to face both sides of the flexible printed wiring board, and providing an adhesive layer on inner surfaces of the pair of thin plate portions; placing the flexible printed wiring board in the case; a step of performing bonding using the adhesive layers provided on the inner sides of the pair of thin plate portions; The present invention is characterized by having the following.

[0016] In this way, the adhesive layer is provided on the inner side of the pair of flexible thin plate portions, and after the flexible printed wiring board is placed, a sealed structure can be obtained simply by bonding with the adhesive layer.

[0017] The method may further include a step of manufacturing the flexible printed wiring board using a base film and a cover film having different widths in the short side direction at least in the region bonded by the adhesive layer.

[0018] It is also preferable to manufacture the flexible printed wiring board so that the wiring and the cover film are provided on both sides of the base film.

[0019] A supplementary adhesive layer is provided on each side of the flexible printed wiring board so as to protrude on both sides in the short direction of the flexible printed wiring board, and then the flexible printed wiring board is A circuit board may be disposed in the case.

[0020] The above configurations may be combined as much as possible. Effect of the Invention

[0021] As described above, according to the present invention, sufficient sealing performance can be obtained with a simple structure. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram of an apparatus having a sealing structure according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a manufacturing process diagram of the flexible printed wiring board according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a manufacturing process diagram of the sealing structure according to the first embodiment of the present invention. [Figure 4]FIG. 4 is a schematic cross-sectional view of a sealing structure according to a second embodiment of the present invention. [Diagram 5] FIG. 5 is a manufacturing process diagram of a sealing structure according to the third embodiment of the present invention. [Figure 6] FIG. 6 is a manufacturing process diagram of a sealing structure according to the third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions, and the like of the components described in the embodiment are not intended to limit the scope of the present invention unless otherwise specified.

[0024] Example 1 With reference to Figs. 1 to 3, a sealing structure having a flexible printed circuit board (hereinafter referred to as FPC) according to a first embodiment of the present invention and a manufacturing method thereof will be described. Fig. 1 is a schematic diagram of an apparatus (electronic device) having a sealing structure according to a first embodiment of the present invention, in which Fig. 1(a) is a plan view and Fig. 1(b) is a side view. Fig. 2 is a manufacturing process diagram of an FPC according to a first embodiment of the present invention. In Fig. 2, each member is shown in a schematic cross-sectional view (corresponding to the cross-sectional view along the line AA in Fig. 1). Fig. 3 is a manufacturing process diagram of a sealing structure according to a first embodiment of the present invention. In Fig. 3, each member is shown in a schematic cross-sectional view (corresponding to the cross-sectional view along the line AA in Fig. 1). In addition, for the adhesive layers shown in each figure, the reference numerals of the adhesive layers before bonding have "F" added after the numbers, and the reference numerals of the adhesive layers after bonding (melted and cured) are shown only by the numbers.

[0025] <Devices with sealed structures> The device 10 shown in Fig. 1 includes an FPC 100 and a case 200. Regarding the device 10 according to this embodiment, various electronic devices can be applied, and a plurality of electronic components are provided inside the case 200. The case 200 integrally includes a case main body 210 and a pair of flexible thin plate portions 220. Regarding the case main body 210, depending on the device 10, it may be made of a highly rigid material or may be made of a highly flexible material similar to the thin plate portions 220. When the materials of the case main body 210 and the pair of thin plate portions 220 are different, they may be joined after being molded separately, or may be molded simultaneously by integral molding. When the materials of the case main body 210 and the pair of thin plate portions 220 are the same, integral molding is preferable.

[0026] As shown in Fig. 3, an opening O is provided in the case main body 210. The FPC 100 is used in a state where a part of it is drawn out through the opening O from inside the case 200. Thereby, one end of each of the plurality of wirings 130 provided on the FPC 100 is connected to various electronic components inside the case 200, and the other end can be connected to a power source and various devices (not shown) outside the case 200. The pair of flexible thin plate portions 220 are provided on the case main body 210 along the opening O and facing both sides of the FPC 100 respectively.

[0027] <Sealed Structure Having an FPC and Manufacturing Method Thereof> Although the manufacturing method of the FPC 100 is a known technique, a representative manufacturing method will be briefly described with reference to FIG. 2. First, an etching process is performed to provide a desired circuit (wiring 130) on a material having a metal foil (such as copper foil) provided on a base film 110 via an adhesive layer 120F. As a result, a plurality of wirings 130 are formed on the base film 110 (see FIG. 2(a)). A cover film 140 (see FIG. 2(a)) having an adhesive layer 150F provided on one side is adhered to the base film 110 obtained in this manner in a superimposed state (see FIG. 2(b)). The adhesive layer 120F and the adhesive layer 150F are made of a thermosetting resin material, and are melted and then hardened by heating the base film 110 and the cover film 140 in a superimposed state while being pressurized. As a result, the base film 110 and the cover film 140 are fixed by the hardened adhesive layer 120 and the adhesive layer 150. Furthermore, the multiple wirings 130 are sandwiched between the base film 110 and the cover film 140 and are protected from the outside.

[0028] As described above, the case 200 is provided with a pair of thin plate parts 220. The adhesive layer 230F is provided on the inner surfaces of the pair of thin plate parts 220. For example, the adhesive layer 230F can be made of a thermosetting resin film or the like, and two film-like adhesive layers 230F may be attached to the inner surfaces of the pair of thin plate parts 220, respectively.

[0029] Next, the FPC 100 is placed in the case 200. As a result, a part of the FPC 100 is pulled out from inside the case 200 through the opening O (see FIG. 3(a)). After that, the pair of thin plate parts 220 are bonded by the adhesive layers 230F provided on the inner sides thereof. As described above, when the adhesive layers 230F are made of a thermosetting resin film, the pair of thin plate parts 220 are heated while being pressed in a superimposed state, whereby the pair of adhesive layers 230F melt and then harden, and the pair of thin plate parts 220 are bonded together.

[0030] As a result, the gap between the inner wall surface of the opening O provided in the case 200 and the FPC 100 is filled and sealed by the hardened adhesive layer 230. That is, the hardened adhesive layer 230 functions as a seal to seal the gap. It is preferable that the pair of thin plate parts 220 are connected near the base on the case body 210 side and are separated at the tip side (see FIG. 1(b)). This makes it easier to insert the FPC 100 into the opening O by spreading the pair of thin plate parts 220 apart. By providing the adhesive layer 230F up to the base position where the pair of thin plate parts 220 are connected to each other, the gap between the inner wall surface of the opening O and the FPC 100 can be more reliably filled by the hardened adhesive layer 230.

[0031] As described above, in the sealed structure according to this embodiment, the adhesive layer 230F is provided beforehand on the inner surfaces of the pair of thin plate portions 220, and with the FPC 100 placed, adhesion is performed by the adhesive layer 230F provided on each of the inner surfaces of the pair of thin plate portions 220. This seals the gap between the inner wall surface of the opening O provided in the case 200 and the FPC 100. Note that this embodiment shows a configuration in which adhesion is performed by the adhesive layer 230F after the FPC 100 is placed on the already-fabricated case main body 210. However, the present invention also includes a configuration in which the fabrication of the case and adhesion by the adhesive layer are performed in the same process. For example, when the case is made of a plurality of flexible members (for example, film-like members) and these When a case is made by bonding multiple components with an adhesive (such as heat sealing), the case can be made and the adhesive layer for providing the sealed structure can be bonded in the same process. That is, an adhesive layer for making the case and an adhesive layer for providing the sealed structure are provided for multiple components, and an FPC is arranged so that it passes through the position that will become the opening of the case from inside the case, and then the adhesive layers of each part are bonded by heat sealing or the like, so that the sealed structure can be provided in the same process as the case is made. Note that when such a configuration is adopted, the boundary between the case main body and the pair of thin plate parts may not always be clear.

[0032] <Advantages of the sealing structure and manufacturing method thereof according to this embodiment> According to the sealed structure of this embodiment, the sealed structure can be obtained simply by providing a pair of thin plate parts 220 on the case 200 and providing an adhesive layer 230F on the inside of the pair of thin plate parts 220. According to the manufacturing method of this embodiment, the adhesive layer 230F is provided on the inside of the pair of flexible thin plate parts 220, and the sealed structure can be obtained simply by bonding with the adhesive layer 230F after the FPC 100 is placed.

[0033] Moreover, according to this embodiment, the FPC 100 can be sealed by being sandwiched between the pair of thin plate parts 220. In this manner, the sealing structure according to this embodiment is a structure in which the hardened adhesive layer 230 is provided in the narrow gap between the FPC 100 and the thin plate parts 220, so that only a narrow space is required. Accordingly, the sealing performance is also improved.

[0034] As described above, the sealing structure according to this embodiment can prevent water, dust, and the like from entering the case 200. Here, for example, in-vehicle electronic devices may be exposed to exhaust gas (H2S, SO2, and the like) discharged from the engine room, gas generated from the EV system battery, and salt-containing water vapor near the coast. Therefore, it is necessary to prevent these from entering the case 200. The sealing structure according to this embodiment is a structure in which the hardened adhesive layer 230 is provided in the narrow gap between the FPC 100 and the thin plate portion 220, so it is more effective in preventing the intrusion of the exhaust gas and the like than a sealing structure using a grommet or the like. In order to further prevent these from entering, it is preferable to use an olefin-based, fluorine-based, phenol-based, or other resin material that has excellent chemical resistance and solvent resistance as the material of the adhesive layer 230F. In this way, the material of the adhesive layer 230F may be appropriately selected depending on the environment in which the device (electronic device) is used.

[0035] In the illustrated example, the FPC 100 is configured such that the wiring 130 and the cover film 140 are provided only on one side of the base film 110 (so-called single-sided FPC). However, the sealing structure and the manufacturing method thereof according to this embodiment can also be applied to a configuration in which the wiring 130 and the cover film 140 are provided on both sides of the base film 110 (so-called double-sided FPC) or to an FPC with a multi-layer structure in which films and wiring are provided across multiple layers.

[0036] Here, depending on the overall thickness of the FPC 100, the material and thickness of the adhesive layer 230F, etc., the gap between the inner wall surface of the opening O and the FPC 100 may not be filled sufficiently by the adhesive layer 230. For example, when the adhesive layer 230F is made of a thermosetting resin film as described above, the pair of thin plate parts 220 are heated while being pressed in a state of being overlapped, so that the pair of adhesive layers 230F melt and flow, and the gap is filled. The vicinity surrounded by X in FIG. 3(b) is located away from the pair of thin plate parts 220, and the material of the molten adhesive layer 230F may not reach the vicinity, and a gap may be formed partially. Therefore, in the following Examples 2 and 3, a sealing structure in which measures are taken in the case where such a defect may occur will be described.

[0037] Example 2 Fig. 4 shows a second embodiment of the present invention. In this embodiment, the configuration of the FPC is different from that of the first embodiment. Since the other configurations and functions are the same as those of the first embodiment, the same components are given the same reference numerals and the description thereof will be omitted as appropriate.

[0038] In the above-mentioned Example 1, a case where an FPC 100 is adopted in which the widths of the base film 110 and the cover film 140 in the short-side direction are the same as in the configuration of a general FPC is shown. In contrast to this, in this embodiment, a configuration is shown in which an FPC is adopted in which the widths of the base film and the cover film in the short-side direction are different at least in the region where adhesion is performed by the adhesive layer 230. Note that in the region other than the region where adhesion is performed by the adhesive layer 230F, the widths of the base film and the cover film in the short-side direction may be the same.

[0039] FIG. 4 is a schematic cross-sectional view of a sealing structure according to a second embodiment of the present invention, and corresponds to the cross-sectional view of FIG. 1(a) shown in the first embodiment. In the FPC 100A shown in FIG. 4(a), the width in the short-side direction of the base film 110A and the adhesive layer 120A is wider than the width in the short-side direction of the cover film 140A and the adhesive layer 150A at least in the region where the adhesive layer 230 is bonded. As a result, a step is formed on both sides of the FPC 100A. Therefore, in the bonding process by the adhesive layer 230F, the bending points of the pair of thin plate parts 220 are different between the base film 110A side and the cover film 140A side. Therefore, the distance from the pair of thin plate parts 220 to the point where the distance to the FPC 100A is the longest can be shortened compared to the first embodiment. As a result, the gap between the inner wall surface of the opening O and the FPC 100A can be sufficiently filled by the adhesive layer 230, and the occurrence of a gap can be suppressed.

[0040] The manufacturing method of the FPC 100A and the manufacturing method of the sealed structure including the FPC 100A are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0041] In the FPC 100B shown in Fig. 4(b), the width in the short side direction of the base film 110B and the adhesive layer 120B is narrower than the width in the short side direction of the cover film 140B and the adhesive layer 150B at least in the region where adhesion is performed by the adhesive layer 230. As a result, steps are formed on both side surfaces of the FPC 100B. Therefore, the same effect as that of the FPC 100A shown in Fig. 4(a) can be obtained. Note that the manufacturing method of the FPC 100B and the manufacturing method of the sealed structure including the FPC 100B are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0042] The FPC 100C shown in FIG. 4(c) is a so-called double-sided FPC. In this FPC 100C, at least in the area bonded by the adhesive layer 230, the width in the short side direction of the base film 110C and the adhesive layer 120C is wider than the width in the short side direction of the cover film 140C and the adhesive layer 150C provided on both sides. As a result, steps are formed on both sides of the FPC 100C. Therefore, the same effect as that of the FPC 100A shown in FIG. 4(a) can be obtained. Note that the manufacturing method of the FPC 100C and the manufacturing method of the sealed structure including the FPC 100C are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0043] Although not shown in the figures, the sealing structure and the manufacturing method thereof according to the present embodiment can also be applied to a multi-layer FPC in which films and wiring are provided across multiple layers. In this case, it is advisable to adopt a configuration in which the width of the film is wide at the center in the thickness direction of the FPC and the width of the film narrows as it approaches both sides of the FPC.

[0044] Example 3 5 and 6 show a third embodiment of the present invention. In this embodiment, the configuration relating to the FPC is different from that of the first embodiment. Since the other configurations and functions are the same as those of the first embodiment, the same components are given the same reference numerals and the description thereof will be omitted as appropriate. Omitted.

[0045] 5 and 6 are manufacturing process diagrams of a sealing structure according to Example 3 of the present invention. In addition, in Fig. 5 and Fig. 6, each member is shown in a schematic cross-sectional view (corresponding to the cross-sectional view taken along line AA in Fig. 1).

[0046] In this embodiment, first, the FPC 100 is manufactured (see FIG. 5(a)). The manufacturing method of the FPC 100 is as described in the first embodiment. Next, the supplementary adhesive layer 160F is provided on both sides of the FPC 100 so as to protrude on both sides in the short direction of the FPC 100 (see FIG. 5(b)). This point is different from the first embodiment. Thereafter, as in the first embodiment, the FPC 100 is placed in the case (see FIG. 6(a)), and adhesion is performed by the adhesive layer 230F provided on the inner side of the pair of thin plate parts 220 (see FIG. 6(b)), and a sealing structure is provided. Note that in FIG. 6, only the pair of thin plate parts 220 are shown for the case, and the case body is omitted. In this embodiment, the hardened supplementary adhesive layer 160 and adhesive layer 230 seal the gap between the inner wall surface of the opening O provided in the case 200 and the FPC 100.

[0047] As described above, in this embodiment, before bonding with the adhesive layer 230F, the supplementary adhesive layers 160F are provided in advance on both sides of the FPC 100 so as to protrude on both sides in the short direction of the FPC 100. By providing the supplementary adhesive layers 160F in this manner, it is possible to prevent the occurrence of a portion on the side surface side of the FPC 100 near the center in the thickness direction of the FPC 100 where the adhesive layer 230 is not filled.

[0048] The sealing structure and its manufacturing method according to this embodiment can also be applied to a configuration in which wiring 130 and cover film 140 are provided on both sides of base film 110 (so-called double-sided FPC) and a multi-layered FPC in which films and wiring are provided across multiple layers. That is, in the case of a double-sided FPC or a multi-layered FPC, the supplementary adhesive layer 160F may be provided in advance on the outermost film as described above. [Explanation of symbols]

[0049] 10: Equipment 100, 100A, 100B, 100C: FPC 110, 110A, 110B, 110C: Base film 120,120A,120B,120C,120F: Adhesive layer 130: Wiring 140, 140A, 140B, 140C: Cover film 150,150A,150B,150C,150F: Adhesive layer 160,160F:Supplementary adhesive layer 200: Case 210: Case body 220: Thin plate part 230,230F: Adhesive layer O: Opening

Claims

1. A sealing structure for sealing a gap between an inner wall surface of an opening provided in a case and a flexible printed wiring board that is used in a state where a part of the flexible printed wiring board is pulled out from inside the case through the opening, the case includes a pair of flexible thin plate portions that are aligned with the opening and that face both sides of the flexible printed wiring board, In the opening, a supplementary adhesive layer is provided in advance on both sides of the flexible printed wiring board, A sealed structure characterized in that an adhesive layer is provided in advance on the inner surfaces of the pair of thin plate portions, and when the flexible printed wiring board is placed, the gap is sealed by bonding using the adhesive layers provided on the inner surfaces of the pair of thin plate portions.

2. The flexible printed wiring board is A base film; Wiring provided on the base film; a cover film attached to the base film so as to cover the wiring; Equipped with 2. The sealing structure according to claim 1, wherein the widths of the base film and the cover film in the short-side direction are different at least in the region bonded by the adhesive layer.

3. The sealing structure according to claim 2 , wherein the wiring and the cover film are provided on both sides of the base film.

4. A sealing structure as described in claim 1, 2 or 3, characterized in that before bonding with the adhesive layer, the supplementary adhesive layer is provided in advance on both sides of the flexible printed wiring board so as to protrude on both sides in the short direction of the flexible printed wiring board.

5. 1. A method for manufacturing a sealed structure for sealing a gap between an inner wall surface of an opening provided in a case and a flexible printed wiring board that is used in a state where a part of the flexible printed wiring board is pulled out from inside the case through the opening, comprising: In the opening, a supplementary adhesive layer is provided in advance on both sides of the flexible printed wiring board, a step of providing a pair of flexible thin plate portions in the case so as to align with the opening and so as to face both sides of the flexible printed wiring board, and providing an adhesive layer on inner surfaces of the pair of thin plate portions; a step of placing the flexible printed wiring board in the case; a step of bonding the pair of thin plate portions with the adhesive layers provided on the inner sides of the pair of thin plate portions; A method for manufacturing a sealed structure, comprising:

6. The method for manufacturing a sealed structure according to claim 5, characterized in that it includes a step of manufacturing the flexible printed wiring board using a base film and a cover film that have different widths in the short side direction at least in the area bonded by the adhesive layer.

7. 7. The method for manufacturing a sealed structure according to claim 6, wherein the flexible printed wiring board is manufactured so that the wiring and the cover film are provided on both sides of the base film.

8. 8. A method for manufacturing a sealed structure according to claim 5, 6 or 7, characterized in that the supplementary adhesive layer is provided on both sides of the flexible printed wiring board so as to protrude on both sides in the short direction of the flexible printed wiring board, and then the flexible printed wiring board is placed in the case.

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