Protective layer of flexible circuit board and preparation method thereof

Abstract

The invention relates to a protective layer of a flexible circuit board and a preparation method thereof, the flexible circuit board comprises a device area, the method comprises the following steps: (1) preparing a device area shaping shell, and arranging an accommodating area capable of accommodating the device area on the flexible circuit board in the device area shaping shell; (2) filling the accommodating area of the device area shaping shell with a protective liquid; (3) inserting the device area into the protective liquid; and (4) after the protection liquid is solidified, shelling the device area shaping shell, and forming a protection layer on the device area. By preparing the glue protection layer, the reliability of the device is improved, and the protection effect is better.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a protective layer of a flexible circuit board and a preparation method thereof. Background Art

[0002] With the need of development, in wearable electronic products, it is usually necessary to protect the devices on the flexible circuit board. For example, the related art discloses a flexible circuit board structure and its manufacturing method, and a display device, wherein the flexible circuit board structure includes: a flexible circuit board; an electronic component connected to the flexible circuit board, the four sides of the electronic component including a first side; a shielding cover for electromagnetic shielding of the electronic component, the shielding cover is arranged on the electronic component, and the shielding cover is at least an unclosed opening side on the first side of the electronic component; and a waterproof adhesive layer, the waterproof adhesive layer is at least filled in the connection position between the electronic component and the flexible circuit board. This invention patent application uses a shielding cover to protect the device, which is costly and increases the height of the device area. Summary of the invention

[0003] Based on this, it is necessary to provide a protective layer for a flexible circuit board and a preparation method thereof to address the above-mentioned technical problems existing in the related technology. By preparing a glue protective layer, the reliability of the device can be improved and the protection effect can be better.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for preparing a protective layer of a flexible circuit board, wherein the flexible circuit board includes a device area, and the method includes:

[0006] (1) preparing a device area molded shell, wherein the device area molded shell has a receiving area inside which can receive the device area on the flexible circuit board;

[0007] (2) Filling the receiving area of ​​the device area molded shell with a protective liquid;

[0008] (3) Insert the device area into the protective liquid;

[0009] (4) After the protective liquid solidifies, the outer shell of the device area is peeled off to form a protective layer on the device area.

[0010] The protective liquid of the present invention is shaped by shaping the outer shell of the device area to generate a complete protective layer. Compared with the added metal / plastic protective layer, it saves costs, and compared with the defect of poor wall hanging performance of the glue coating method, it has a better protection effect and effectively improves the reliability of the device.

[0011] In a feasible implementation, in step (2), the amount of the protective liquid used is 70%-80% of the volume of the containing area. The present invention achieves the purpose of cost saving by controlling the amount of the protective liquid used.

[0012] In a feasible implementation, between step (1) and step (2), there is further step (a): laying an anti-sticking layer in the device area molded shell;

[0013] In a feasible implementation, the device area shaped shell includes a bottom and a side wall, the side wall is arranged around the bottom, the side wall and the bottom form a receiving area, and when the device area is located in the receiving area, the minimum distance between the inner side of the side wall and the device area is 0.5-1.0 mm;

[0014] In a feasible implementation, the minimum distance between the inner side of the bottom and the device area is 0.2-1.0 mm;

[0015] In a feasible implementation, the side wall includes a first wall and a second wall located on a side of the first wall close to the bottom, the second wall is connected to the bottom, and the inner side of the second wall is set as a curved surface;

[0016] In a feasible implementation, a drainage channel is provided at the upper end of the first wall;

[0017] In a feasible implementation, the anti-sticking layer includes an insulating tape;

[0018] In a feasible implementation, the protective liquid includes half-sealing glue, full-sealing glue or underfill glue.

[0019] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0020] A method for preparing a protective layer of a flexible circuit board, wherein the flexible circuit board includes a device area, and the method includes:

[0021] (1) preparing a device area molded shell, wherein the device area molded shell has a receiving area inside which can receive the device area on the flexible circuit board;

[0022] (2) inserting the device area into the receiving area;

[0023] (3) Filling the protective liquid into the receiving area of ​​the device area molded shell;

[0024] (4) After the protective liquid solidifies, the outer shell of the device area is peeled off to form a protective layer on the device area.

[0025] The protective liquid of the present invention is shaped by shaping the outer shell of the device area to generate a complete protective layer. Compared with the added metal / plastic protective layer, it saves costs, and compared with the defect of poor wall hanging performance of the glue coating method, it has a better protection effect and effectively improves the reliability of the device.

[0026] In a feasible implementation, a liquid injection port is provided at the upper end of the device area molding shell.

[0027] In a feasible implementation, the device area shaping shell in step (1) includes a bottom and a side wall, the side wall is arranged around the bottom, and the side wall and the bottom form a containing area. When the device area is located in the containing area, the minimum distance between the inner side of the side wall and the device area is 0.5-1.0 mm. The present invention controls the thickness of the protective layer by controlling the distance between the inner side of the side wall and the device area.

[0028] In a feasible implementation, the minimum distance between the inner side of the bottom and the device area is 0.2-1.0 mm. The present invention controls the thickness of the protective layer by controlling the height of the receiving area and the distance between the device area.

[0029] In a feasible implementation, the side wall includes a first wall and a second wall located on the side of the first wall close to the bottom, the second wall is connected to the bottom, and the inner side of the second wall is set as a curved surface. The present invention is set here to facilitate the subsequent separation of the protective layer from the device area molded shell.

[0030] In a feasible implementation, a drainage channel is provided at the upper end of the first wall. The present invention facilitates the drainage of excess liquid through the drainage channel.

[0031] In a feasible implementation, between step (1) and step (2), there is further included step (a): laying an anti-sticking layer in the device area shaped shell. The anti-sticking layer provided in the present invention facilitates the subsequent separation of the protective layer from the device area shaped shell.

[0032] In a possible implementation, the anti-sticking layer includes an insulating tape.

[0033] In a feasible implementation, the protective liquid includes one of half-sealing glue, full-sealing glue or underfill glue.

[0034] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0035] A protective layer for a flexible circuit board is prepared by the method described above.

[0036] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0037] A flexible circuit board comprises a device area, and the device area is coated with a protective layer prepared by the method as described above.

[0038] Due to the adoption of the above technical solution, the present invention has the following advantages compared with the related art:

[0039] 1. The protection method of the present invention does not need to install a metal / plastic shielding cover as in the related art, which saves costs and does not increase the height of the device area;

[0040] 2. Compared with the gluing method in the related art, which has the defects of easy flow of glue and poor wall hanging performance, the protection method of the present invention improves the reliability of the device by preparing a glue protective layer, and has a better protection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a flexible circuit board failing in water during an energized immersion test in the related art;

[0042] Figure 2 This is a schematic diagram of the structure of the device area molded housing according to Embodiment 1 of the present invention;

[0043] Figure 3 This is a method step diagram of Example 1 of the present invention;

[0044] Figure 4 This is a schematic diagram of the structure of the device area molded housing according to Embodiment 2 of the present invention;

[0045] Figure 5 This is a method step diagram of Embodiment 2 of the present invention;

[0046] Figure 6 This is a schematic diagram of the structure of the device area molded housing according to Embodiment 3 of the present invention;

[0047] Figure 7 This is a schematic diagram of the structure of the device area molded housing according to Embodiment 4 of the present invention;

[0048] Figure 8 This is a method step diagram of Embodiment 4 of the present invention;

[0049] Fig. 9 The figure is a schematic diagram of the structure of an embodiment of the present invention applied on a flexible printed circuit board.

[0050] Among them, 1. substrate; 2. device; 3. device area molded shell; 31. bottom; 32. first wall; 33. second wall; 4. protective layer; 5. anti-sticking layer; 6. drainage hole; 7. injection port. DETAILED DESCRIPTION

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0052] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are for illustrative purposes only.

[0053] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In this application, " / " means "or".

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0055] With the need of development, in wearable electronic products, flexible circuit boards (FPC) usually have the requirement of power-on immersion test to ensure the anti-interference ability and waterproof and moisture-proof ability of the electronic components on the flexible circuit boards.

[0056] The inventors found in practice that Figure 1 As shown in the figure, in the power immersion experiment, the FPC is powered on, and the FPC device is easily exposed to water and gradually fails to conduct electricity, resulting in a micro short circuit.

[0057] On this basis, in order to better protect the FPC device, the present invention provides a protective layer of a flexible circuit board and a preparation method thereof, wherein the flexible circuit board includes a device area, and the method includes:

[0058] (1) preparing a device area molded shell, wherein the device area molded shell has a receiving area inside which can receive the device area on the flexible circuit board;

[0059] (2) Filling the receiving area of ​​the device area molded shell with a protective liquid;

[0060] (3) Insert the device area into the protective liquid;

[0061] (4) After the protective liquid solidifies, the outer shell of the device area is peeled off to form a protective layer on the device area.

[0062] The protective liquid of the present invention is shaped by shaping the outer shell of the device area to generate a complete protective layer. Compared with the added metal / plastic protective layer, it saves costs, and compared with the defect of poor wall hanging performance of the glue coating method, it has a better protection effect and effectively improves the reliability of the device.

[0063] The FPC adhesive protection method of the present invention is described in detail below in conjunction with specific embodiments.

[0064] Example 1

[0065] like Figure 2-3 As shown, in the method for preparing a protective layer of a flexible circuit board in this embodiment, the flexible circuit board includes a device area, and a device 2 is arranged in the device area. The method includes the following steps:

[0066] (1) A device area shaping shell 3 is prepared. The device area shaping shell 3 has a receiving area inside which can receive the device area on the flexible circuit board. The device area shaping shell 3 has an opening for the device area to enter and exit.

[0067] In this embodiment, if Figure 2 As shown, the device area shaping shell 3 in step (1) is a structure with an opening on the top and a hollow interior. Specifically, the device area shaping shell 3 includes a bottom 31 and a side wall, and the side wall is arranged around the bottom 31. The side wall and the bottom 31 constitute a receiving area for receiving the device area on the flexible circuit board. When the device area is located in the receiving area, the minimum distance between the inner side of the side wall and the device area is 0.5-1.0mm, and more specifically can be 0.5mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 1.0mm.

[0068] The minimum distance between the inner side of the sidewall and the device area is defined as the minimum distance w between the inner side of the sidewall of the device area molded shell 3 and the sidewall of the device 2 arranged in the device area. The present invention controls the thickness of the protective layer 4 by controlling the distance between the inner side of the sidewall and the device area.

[0069] When the device area is located in the accommodating area, the minimum distance between the inner side of the bottom 31 and the device area is 0.2-1.0mm, or 0.3-1.0mm, or 0.5-1.0mm, or more specifically 0.5mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, or 1.0mm.

[0070] The minimum distance between the inner side of the bottom and the device area is defined here as the minimum distance h between the inner side of the bottom 31 of the device area molding shell 3 and the side of the device 2 arranged in the device area away from the flexible circuit board. The present invention controls the thickness of the protective layer 4 by controlling the distance between the inner side of the bottom 31 and the device area. The reason why the present invention limits the above distance is to control the thickness of the finally formed protective layer 4. If the final thickness of the protective layer 4 is too thin, it cannot play a protective effect such as waterproof, moisture-proof, and anti-shielding. If the thickness of the protective layer 4 is too thick, on the one hand, the height of the final product is increased, which is not conducive to the thinness of the equipment. On the other hand, the amount of protective liquid used is increased, which is not conducive to reducing costs.

[0071] In order to make it easier to separate the shielding cover 4 from the device area molded shell 3 later, the device area molded shell 3 is further optimized in this embodiment. The side wall of the device area molded shell 3 includes a first wall 32 and a second wall 33. The second wall 33 is located on the side of the first wall 32 close to the bottom 31. In this embodiment, the first wall 32 is vertically arranged, the second wall 33 is arranged below the first wall 32 and connected to the lower part of the first wall 32, and the second wall 33 is arranged between the first wall 32 and the bottom 31 and connected to the first wall 32 and the bottom 31 respectively. The inner side of the second wall 33 is set as an arc surface. Compared with the angle area formed by the inner side plane of the side wall directly connected to the inner side plane of the bottom 31, in this embodiment, the inner side plane of the first wall 32 and the inner side plane of the bottom 31 are connected by the second wall 33 with the inner side set as an arc surface, which makes it easier to separate the protective layer 4 from the device area molded shell 3.

[0072] (2) Fill the protective liquid into the accommodating area inside the device area molding shell 3 from the opening located above the device area molding shell 3.

[0073] In this embodiment, the protective liquid includes one of half-sealing glue, full-sealing glue or underfill glue.

[0074] In other specific embodiments, the protective liquid may also be any other liquid that can provide the device 2 with waterproof, moisture-proof, shielding-proof and other properties.

[0075] In this embodiment, the amount of the protective liquid used in step (2) is 70%-80% of the liquid volume that the containing area can hold. The present invention achieves the purpose of cost saving by controlling the amount of the protective liquid used.

[0076] (3) Insert the device 2 in the device area fixed on the substrate 1 downward from the opening above the device area molded shell 3 into the protective liquid. Since the amount of protective liquid used is excessive, the protective liquid will fill the entire receiving area and completely wrap the device 2 due to the insertion of the device 2, and may even overflow from the top of the device area molded shell 3, so that a complete protective layer 4 will be formed in the end. This is why the present invention needs to control the amount of protective liquid in step (2) to prevent unnecessary waste caused by excessive use of protective liquid.

[0077] (4) After the protective liquid is solidified, the device area molded shell 3 is peeled off to form a protective layer 4 on the device area.

[0078] Example 2

[0079] like Figure 4-5 As shown, in the method for preparing a protective layer of a flexible circuit board in this embodiment, the flexible circuit board includes a device area, and a device 2 is arranged in the device area. The method includes the following steps:

[0080] (1) A device area shaping shell 3 is prepared. The device area shaping shell 3 has a receiving area inside which can receive the device area on the flexible circuit board. The device area shaping shell 3 has an opening for the device area to enter and exit.

[0081] In this embodiment, if Figure 4 As shown, the device area molding shell 3 in step (1) is a structure with an opening on the top and a hollow interior. Specifically, the device area molding shell 3 includes a bottom 31 and side walls, and the side walls are arranged around the bottom 31. The side walls and the bottom 31 constitute a accommodating area for accommodating the device area on the flexible circuit board.

[0082] When the device area is located in the accommodating area, the minimum distance between the inner side of the side wall and the device area is 0.5-1.0 mm, and more specifically can be 0.5 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, or 1.0 mm.

[0083] The minimum distance between the inner side of the sidewall and the device area is defined as the minimum distance w between the inner side of the sidewall of the device area molded shell 3 and the sidewall of the device 2 arranged in the device area. The present invention controls the thickness of the protective layer 4 by controlling the distance between the inner side of the sidewall and the device area.

[0084] When the device area is located in the accommodating area, the minimum distance between the inner side of the bottom 31 and the device area is 0.2-1.0mm, or 0.3-1.0mm, or 0.5-1.0mm, or more specifically 0.5mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, or 1.0mm.

[0085] The minimum distance between the inner side of the bottom and the device area is defined as the minimum distance h between the inner side of the bottom 31 of the device area molded housing 3 and the side of the device 2 arranged in the device area away from the flexible circuit board. The present invention controls the thickness of the protective layer 4 by controlling the distance between the inner side of the bottom 31 and the device area.

[0086] The reason why the present invention limits the above distance is to control the thickness of the final formed protective layer 4. If the final thickness of the protective layer 4 is too thin, it cannot play a protective role such as waterproof, moisture-proof, and anti-shielding. If the thickness of the protective layer 4 is too thick, on the one hand, the height of the final product is increased, which is not conducive to the thinness of the equipment. On the other hand, the amount of protective liquid used is increased, which is not conducive to reducing costs.

[0087] In order to make it easier to separate the protective layer 4 from the device area shaping shell 3 later, the device area shaping shell 3 is further optimized in this embodiment. The side wall of the device area shaping shell 3 includes a first wall 32 and a second wall 33. The second wall 33 is located on the side of the first wall 32 close to the bottom 31. In this embodiment, the first wall 32 is vertically arranged, the second wall 33 is arranged below the first wall 32 and connected to the lower part of the first wall 32, and the second wall 33 is arranged between the first wall 32 and the bottom 31 and connected to the first wall 32 and the bottom 31 respectively. The inner side of the second wall 33 is set as an arc surface. Compared with the angle area formed by the inner plane of the side wall directly connected to the inner plane of the bottom 31, in this embodiment, the inner plane of the first wall 32 and the inner plane of the bottom 31 are connected by the second wall 33 with the inner side set as an arc surface, which makes it easier to separate the protective layer 4 from the device area shaping shell 3.

[0088] In this embodiment, in order to further facilitate the subsequent separation of the protective layer 4 from the device area molded shell 3, the method further includes step (a): laying an anti-sticking layer 5 in the device area molded shell 3.

[0089] In this embodiment, the anti-adhesion layer 5 includes an insulating tape, the adhesive surface of which is facing the inner side of the device area molded shell 3 and is not completely adhered to the device area molded shell 3, so as to facilitate demoulding. In other specific embodiments, the anti-adhesion layer 5 can also be other materials that can achieve the function of facilitating demoulding.

[0090] (2) Fill the protective liquid into the accommodating area inside the device area molding shell 3 from the opening located above the device area molding shell 3.

[0091] In this embodiment, the protective liquid includes one of half-sealing glue, full-sealing glue or underfill glue.

[0092] In other specific embodiments, the protective liquid may also be any other liquid that can provide the device 2 with waterproof, moisture-proof, shielding-proof and other properties.

[0093] In this embodiment, the amount of the protective liquid used in step (2) is 70%-80% of the liquid volume that the containing area can hold. The present invention achieves the purpose of cost saving by controlling the amount of the protective liquid used.

[0094] (3) Insert the device 2 in the device area fixed on the substrate 1 downward from the opening above the device area molded shell 3 into the protective liquid. Since the amount of protective liquid used is excessive, the protective liquid will fill the entire receiving area and completely wrap the device 2 due to the insertion of the device 2, and may even overflow from the top of the device area molded shell 3, so that a complete protective layer 4 will be formed in the end. This is why the present invention needs to control the amount of protective liquid in step (2) to prevent unnecessary waste caused by excessive use of protective liquid.

[0095] (4) After the protective liquid is solidified, the device area molded shell 3 is peeled off to form a protective layer 4 on the device area.

[0096] Example 3

[0097] In order to facilitate the discharge of excess protective liquid and to easily control the amount of protective liquid used, this embodiment further improves the device area molded shell 3 on the basis of embodiment 2.

[0098] like Figure 6 As shown, in this embodiment, one or more drainage channels are provided at the upper end of the first wall 32 of the device area molding shell 3, specifically, they can be drainage holes 6 that pass through the side wall, or they can be drainage grooves provided at the upper end of the first wall 32.

[0099] In order to facilitate the discharge of excess protective liquid, a liquid discharge channel is also provided at a position corresponding to the anti-adhesion layer 5 and the device area molding shell 3 .

[0100] Other configurations of this embodiment are the same or similar to those of Embodiment 2.

[0101] Example 4

[0102] like Figure 7-8 As shown, in the method for preparing a protective layer of a flexible circuit board in this embodiment, the flexible circuit board includes a device area, and a device 2 is arranged in the device area. The method includes the following steps:

[0103] (1) A device area shaping shell 3 is prepared. The device area shaping shell 3 has a receiving area inside which can receive the device area on the flexible circuit board. The device area shaping shell 3 has an opening for the device area to enter and exit.

[0104] In this embodiment, if Figure 7As shown, the device area molding shell 3 in step (1) is a structure with an opening on the top and a hollow interior. Specifically, the device area molding shell 3 includes a bottom 31 and side walls, and the side walls are arranged around the bottom 31. The side walls and the bottom 31 constitute a accommodating area for accommodating the device 2 on the flexible circuit board.

[0105] When the device area is located in the accommodating area, the minimum distance between the inner side of the side wall and the device area is 0.5-1.0 mm, and more specifically can be 0.5 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, or 1.0 mm.

[0106] The minimum distance between the inner side of the side wall and the device area is defined as the minimum distance w (not shown) between the inner side of the side wall of the device area molded shell 3 and the side wall of the device 2 arranged in the device area. The present invention controls the thickness of the protective layer 4 by controlling the distance between the inner side of the side wall and the device area.

[0107] When the device area is located in the accommodating area, the minimum distance between the inner side of the bottom 31 and the device area is 0.2-1.0mm, or 0.3-1.0mm, or 0.5-1.0mm, or more specifically 0.5mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, or 1.0mm.

[0108] The minimum distance between the inner side of the bottom and the device area is defined as the minimum distance h (not shown) between the inner side of the bottom 31 of the device area molded housing 3 and the side of the device 2 arranged in the device area away from the flexible circuit board. The present invention controls the thickness of the protective layer 4 by controlling the height of the accommodating area and the distance between the device 2.

[0109] The reason why the present invention limits the above distance is to control the thickness of the final formed protective layer 4. If the final thickness of the protective layer 4 is too thin, it cannot play a protective role such as waterproof, moisture-proof, and anti-shielding. If the thickness of the protective layer 4 is too thick, on the one hand, the height of the final product is increased, which is not conducive to the thinness of the equipment. On the other hand, the amount of protective liquid used is increased, which is not conducive to reducing costs.

[0110] In order to make it easier to separate the protective layer 4 from the device area shaping shell 3 later, the device area shaping shell 3 is further optimized in this embodiment. The side wall of the device area shaping shell 3 includes a first wall 32 and a second wall 33. The first wall 32 is vertically arranged, and the second wall 33 is located on the side of the first wall 32 close to the bottom 31. In this embodiment, the second wall 33 is arranged below the first wall 32 and connected to the lower part of the first wall 32. The second wall 33 is arranged between the first wall 32 and the bottom 31 and connected to the first wall 32 and the bottom 31 respectively. The inner side of the second wall 33 is set as an arc surface. Compared with the angle area formed by the inner plane of the side wall directly connected to the inner plane of the bottom 31, in this embodiment, the inner plane of the first wall 32 and the inner plane of the bottom 31 are connected by the second wall 33 with the inner side set as an arc surface, which makes it easier to separate the protective layer 4 from the device area shaping shell 3.

[0111] In this embodiment, a liquid injection port 7 is provided on the upper end portion of the first wall 32 of the device area molding shell 3 for injecting liquid into the accommodating area.

[0112] In this embodiment, in order to facilitate the control of the amount of protective liquid, the device area shaping shell 3 is further improved. One or more drainage channels are provided at the upper end of the first wall 32 of the device area shaping shell 3, specifically, they can be drainage holes 6 that penetrate the side wall, or they can be drainage grooves provided at the upper end of the first wall 32. A drainage channel is also provided at the position of the anti-adhesion layer 5 corresponding to the device area shaping shell 3.

[0113] In this embodiment, in order to further facilitate the subsequent separation of the protective layer 4 from the device area molded shell 3, the method further includes step (a): laying an anti-sticking layer 5 in the device area molded shell 3.

[0114] In this embodiment, the anti-adhesion layer 5 includes an insulating tape, the adhesive surface of which is facing the inner side of the device area molded shell 3 and is not completely adhered to the device area molded shell 3, so as to facilitate demoulding. In other specific embodiments, the anti-adhesion layer 5 can also be other materials that can achieve the function of facilitating demoulding.

[0115] (2) Insert the device area into the accommodating area from the opening above the device area molded housing 3.

[0116] (3) Fill the containing area of ​​the device area molding shell 3 with protective liquid.

[0117] In this embodiment, the protective liquid includes one of half-sealing glue, full-sealing glue or underfill glue.

[0118] In other specific embodiments, the protective liquid may also be any other liquid that can provide the device 2 with waterproof, moisture-proof, shielding-proof and other properties.

[0119] In this embodiment, when the protection liquid starts to flow out of the liquid discharge channel, the liquid intake is stopped. This arrangement can more easily control the amount of protection liquid used to achieve the purpose of cost saving.

[0120] (4) After the protective liquid is solidified, the device area molded shell 3 is peeled off to form a protective layer 4 on the device area.

[0121] Example 5

[0122] like Fig. 9 As shown, in this embodiment, a protective layer is provided on a flexible circuit board, and the protective layer is prepared by the FPC gluing protection method of embodiment 3 or embodiment 4.

[0123] The protective liquid of the present invention is shaped by the device area shaping shell 3. When dispensing glue, the glue is applied inside the device area shaping shell 3 but not on the device 2. The device 2 is inserted downward into the glue to generate a complete protective layer 4 to prevent the glue from flowing. Compared with the additional metal / plastic shielding cover, the cost is saved. Compared with the defect of poor wall hanging performance of the glue coating method, the protection effect is better, and the reliability of the device is effectively improved.

[0124] The present invention also provides a flexible circuit board, including a device area, and the device area is coated with a protective layer prepared by the FPC glue coating protection method of Example 3 or Example 4.

[0125] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0126] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a protective layer of a flexible circuit board, wherein the flexible circuit board includes a device area, characterized in that: The method comprises: (1) preparing a device area forming shell, wherein the device area forming shell has a receiving area inside which can receive the device area on the flexible circuit board; (2) filling a protective liquid into the receiving area of ​​the device area molded shell; (3) inserting the device area into the protective liquid; (4) After the protective liquid is solidified, the outer shell of the device area is peeled off to form a protective layer in the device area.

2. The method according to claim 1, characterized in that In the step (2), the amount of the protective liquid is 70%-80% of the volume of the containing area; Preferably, between step (1) and step (2), the method further comprises step (a): laying an anti-sticking layer in the device area shaped shell; Preferably, the device area shaped shell comprises a bottom and a side wall, the side wall is arranged around the bottom, the side wall and the bottom constitute the accommodating area, and when the device area is located in the accommodating area, the minimum distance between the inner side of the side wall and the device area is 0.5-1.0 mm; Preferably, the minimum distance between the inner side of the bottom and the device area is 0.2-1.0 mm; Preferably, the side wall includes a first wall and a second wall located on a side of the first wall close to the bottom, the second wall is connected to the bottom, and the inner side of the second wall is set as a curved surface; Preferably, a drainage channel is provided at the upper end of the first wall; Preferably, the anti-sticking layer comprises an insulating tape; Preferably, the protective liquid includes half-sealing glue, full-sealing glue or underfill glue.

3. A method for preparing a protective layer of a flexible circuit board, wherein the flexible circuit board includes a device area, characterized in that: The method comprises: (1) preparing a device area forming shell, wherein the device area forming shell has a receiving area inside which can receive the device area on the flexible circuit board; (2) inserting the device area into the receiving area; (3) filling the containing area of ​​the device area molded shell with a protective liquid; (4) After the protective liquid is solidified, the outer shell of the device area is peeled off to form a protective layer in the device area.

4. The method according to claim 3, characterized in that The upper end of the device area molding shell is provided with a liquid injection port.

5. The method according to claim 3, characterized in that: The device area shaped shell comprises a bottom and a side wall, the side wall is arranged around the bottom, the side wall and the bottom constitute the accommodating area, and when the device area is located in the accommodating area, the minimum distance between the inner side of the side wall and the device area is 0.5-1.0 mm; Preferably, the minimum distance between the inner side of the bottom and the device region is 0.2-1.0 mm.

6. The method according to claim 5, characterized in that The side wall includes a first wall and a second wall located on a side of the first wall close to the bottom, the second wall is connected to the bottom, and the inner side of the second wall is set as a curved surface; Preferably, a drainage channel is provided at the upper end of the first wall.

7. The method according to claim 3, characterized in that The method further comprises step (a) between step (1) and step (2): laying an anti-sticking layer in the device area shaped shell; Preferably, the anti-sticking layer comprises an insulating tape.

8. The method according to claim 3, characterized in that The protective liquid includes half-sealing glue, full-sealing glue or bottom-filling glue.

9. A protective layer for a flexible circuit board, characterized in that: The method is prepared by the method according to any one of claims 1 to 8.

10. A flexible circuit board, comprising a device area, characterized in that: The device area is coated with a protective layer prepared by the method according to any one of claims 1 to 8.

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