Packaging structure of flexible circuit board and display device

Abstract

The application discloses a packaging structure of a flexible circuit board and a display device. The packaging structure comprises a flexible substrate, a conductive layer on the flexible substrate, a protective layer covering the conductive layer, a connecting end on the conductive layer, the connecting end being exposed from the protective layer to connect an external circuit, and a water absorption layer on the protective layer and arranged adjacent to the connecting end. The distance between the water absorption layer and the corresponding connecting end is not greater than 2.5 mm. The connecting end comprises an input end and an output end. The input end and the output end each comprise an anisotropic conductive film. The water absorption layer comprises a first water absorption layer and a second water absorption layer. The first water absorption layer is arranged adjacent to the input end, and the second water absorption layer is arranged adjacent to the output end. By arranging the water absorption layer near the connecting end of the packaging structure, the problem that the input end and the output end are exposed to a humid environment and are prone to oxidation and corrosion due to dislocation and warping of the partial conductive layer at the edge of the input end and the output end caused by a warm and pressurized fitting process is effectively solved.

Description

Technical Field

[0001] This utility model relates to the field of microelectronic device technology, and more specifically, to a flexible circuit board packaging structure and display device. Background Technology

[0002] In recent years, various electronic products have gradually become thinner, smaller, and lighter. In response to these demands, various technical solutions have been developed to install semiconductor chips in a small area of ​​electronic products with high density, such as using COF (ChipOn Film) flexible circuit boards.

[0003] Display devices are widely used in people's daily lives. For example, mobile phones, smartwatches, tablets, monitors, televisions, and in-vehicle infotainment screens are ubiquitous. With the development of display technology, the requirements for high screen-to-body ratio, lightweight, high durability, and high reliability are also increasing. Display devices typically include display panels, flexible printed circuit boards (FPCBs), and printed circuit boards (PCBs). Figure 1 As shown, one end of the flexible circuit board 3 is connected to the display panel 1, and the other end is connected to the printed circuit board 2. (See attached diagram) Figure 1 The connection area shown in the dashed box is designed to meet the requirements of narrow bezels, light weight, high durability, and high reliability. A strong electrical connection is achieved by bonding the connection ends of the flexible circuit board 3 to the corresponding connection areas of the display panel 1 or printed circuit board 2 using an anisotropic conductive film (ACF) followed by heating and pressurization. However, the flexible circuit board 3 comprises multiple layers of different materials. During the bonding process under heat and pressure, these different materials undergo varying degrees of deformation and stretching. This results in misalignment and warping of the conductive layers in certain areas at the edges of the input and output terminals, exposing small portions of the conductors in the misalignment gaps to the air. This exposure accelerates oxidation and corrosion, causing signal abnormalities and ultimately damaging the flexible circuit board and malfunctioning the display device.

[0004] Therefore, there is an urgent need to design a flexible circuit board packaging structure and display device to improve the above problems and enhance the product's lifespan and stability. Utility Model Content

[0005] The purpose of this invention is to provide a flexible circuit board packaging structure and display device to solve the problems of poor product stability and easy oxidation and corrosion of circuits leading to failure in the prior art, thereby enhancing the product's lifespan and reliability.

[0006] According to one aspect of the present invention, a packaging structure for a flexible circuit board is provided, comprising: a flexible substrate; a conductive layer located on the flexible substrate; a protective layer covering the conductive layer; a connection terminal located on the conductive layer, the connection terminal being exposed from the protective layer to connect to an external circuit; and a water-absorbing layer located on the protective layer and disposed adjacent to the connection terminal; wherein the distance between the water-absorbing layer and the corresponding connection terminal is not greater than 2.5 mm.

[0007] In the above-described packaging structure, the connection terminal includes an input terminal and an output terminal, and both the input terminal and the output terminal include an anisotropic conductive film.

[0008] Optionally, the absorbent layer includes a first absorbent layer and a second absorbent layer, wherein the first absorbent layer is disposed adjacent to the input end and the second absorbent layer is disposed adjacent to the output end.

[0009] Optionally, the system may also include a chip disposed on the flexible substrate and electrically connected to the conductive layer.

[0010] Optionally, the periphery of the chip is also filled with insulating filler adhesive.

[0011] Optionally, the conductive layer includes: a first conductive layer and a second conductive layer, wherein the first conductive layer is disposed on the flexible substrate, and the second conductive layer covers the first conductive layer.

[0012] Optionally, the thickness of the second conductive layer is 0.16 μm-0.20 μm.

[0013] According to another aspect of the present invention, a display device is also provided, comprising: a display panel; a packaging structure of the aforementioned flexible circuit board, wherein the output end of the packaging structure is connected to the display panel; and a circuit board connected to the input end of the packaging structure.

[0014] In the aforementioned display device, at least one of the display panel and the circuit board is connected to the encapsulation structure of the flexible circuit board by applying an anisotropic conductive film and then heating and pressurizing it. The encapsulation structure of the flexible circuit board has a water-absorbing layer at the corresponding connection end.

[0015] The flexible circuit board packaging structure provided in this embodiment effectively solves the problem of misalignment and warping of the conductive layers at the edges of the input and output terminals, which are easily oxidized and corroded when exposed to humid air due to the heat-pressurized bonding process, by setting a water-absorbing layer near the connection end of the packaging structure. When the flexible circuit board packaging structure is connected to the printed circuit board or display panel under heat and pressure, the water-absorbing layer can absorb moisture from the surrounding air in a timely manner, preventing it from accumulating near the gaps caused by material deformation, and controlling the ambient humidity near the conductive layer exposed by the gaps within a safe range. In particular, by using a close arrangement of the water-absorbing layer and the connection end with a spacing of no more than 2.5 mm, the water absorption range of the polymer water-absorbing material can fully cover the gap area, significantly reducing the risk of accelerated oxidation and corrosion of the conductive layer exposed from the gap due to moisture. Meanwhile, the heat generated during operation by this encapsulation structure promotes the evaporation of moisture in the absorbent layer, allowing the absorbent layer to repeatedly absorb moisture when the device is not in use or when it is humid, maintaining a dry environment. Especially in high humidity areas, the application of this encapsulation structure to display devices significantly improves the reliability and lifespan of the product and effectively reduces the occurrence of related failures. Attached Figure Description

[0016] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the present invention with reference to the accompanying drawings.

[0017] Figure 1 A schematic diagram of an existing display device is shown;

[0018] Figure 2 A schematic diagram showing the packaging structure of the flexible circuit board according to an embodiment of the present invention;

[0019] Figure 3 This diagram shows a partial cross-sectional view of the flexible circuit board after the packaging structure of the present invention has been connected according to an embodiment of the present invention.

[0020] Figure 4 A schematic diagram of a display device according to an embodiment of the present invention is shown. Detailed Implementation

[0021] The present invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. Furthermore, some well-known parts may not be shown. For simplicity, the semiconductor package structure obtained after several steps can be depicted in a single figure.

[0022] It should be understood that when describing a structure, when referring to a layer or region as being "above" or "on top of" another layer or region, it can mean that it is directly above the other layer or region, or that it contains other layers or regions between it and the other layer or region. Furthermore, if the device is flipped, the layer or region will be located "below" or "under" the other layer or region.

[0023] To describe a situation where it is located directly on another layer or another area, this article will use the expressions "directly on top of" or "on and adjacent to".

[0024] Many specific details, such as the structure, materials, dimensions, processing techniques, and methods of the devices, are described below to provide a clearer understanding of the present invention. However, as those skilled in the art will understand, the present invention may be implemented without following these specific details.

[0025] This utility model can be presented in various forms, some of which will be described below.

[0026] Figure 2 This diagram illustrates the packaging structure of a flexible circuit board according to an embodiment of the present invention. The packaging structure includes: a flexible substrate 110, a protective layer 130, an input terminal 141, an output terminal 142, an anisotropic conductive film 143 for bonding the input terminal, an anisotropic conductive film 144 for bonding the output terminal, a first absorbent layer 151, a second absorbent layer 152, a chip 160, and a filler adhesive 161. A conductive layer is disposed on the flexible substrate 110, which is covered and invisible by the protective layer 130. The input terminal 141 and the output terminal 142 are respectively disposed on the left and right sides of the flexible substrate 110. The chip 160 is located on the flexible substrate 110 and electrically connected to the conductive layer. The input terminal 141 and the output terminal 142 are respectively located on the left and right sides of the chip 160. A filler adhesive 161 is also disposed on the edge of the chip 160 to protect and further fix the connection between the chip 160 and the conductive layer. Input terminal 141 and output terminal 142 are both connected to the conductive layer, for example. Input terminal 141 is used to connect to the printed circuit board, and output terminal 142 is used to connect to the display panel. Specifically, input terminal 141 and output terminal 142 are both bonded to anisotropic conductive films 143 and 144. They are bonded to the outside and electrically connected by heating and pressurizing. The anisotropic conductive film is usually composed of a resin matrix (such as thermosetting epoxy resin) and conductive particles dispersed therein (such as nickel, silver, copper nanoparticles or nickel and gold coated polymer particles). By pressurizing and heating, the conductive particles are pressed and contacted in the vertical direction to form a conductive path, while maintaining an insulating state from adjacent electrodes in the horizontal direction. At the same time, the upper / lower bonding components are mechanically fixed by resin curing.

[0027] Because the flexible circuit board's packaging structure includes multiple layers of different materials, when the input terminal 141 and output terminal 142 are bonded together under heat and pressure, the different materials inside the packaging structure will undergo varying degrees of deformation and stretching. This causes some conductive layers at the edges of the input and output terminals to misalign and warp, exposing them to air. To mitigate the oxidation and corrosion of these conductive layers, a first absorbent layer 151 and a second absorbent layer 152 are provided above the protective layer 130 in the packaging structure. The first absorbent layer 151 is, for example, located on the input terminal 141 side, and the second absorbent layer 152 is, for example, located on the output terminal 142 side. The distance D1 between the first absorbent layer 151 and the input terminal 141 is, for example, 1.0 mm, and the distance D2 between the second absorbent layer 152 and the output terminal 142 is, for example, 2.0 mm. To ensure the effectiveness of the absorbent layer, the distance between the absorbent layer and the corresponding connection terminal is no greater than 2.5 mm. The absorbent layer is, for example, made of a high-molecular-weight absorbent material. Specifically, the first absorbent layer 151 and the second absorbent layer 152 need to be set on the protective layer 130 before the flexible circuit board's encapsulation structure is connected to the printed circuit board and the display panel. By setting the absorbent layer, it can be kept in a relatively dry environment, thereby slowing down the oxidation and corrosion of the exposed conductive layer. Furthermore, after the product is put into use, the heat during its operation will promote the evaporation of the water adsorbed in the absorbent layer, so that the absorbent layer can repeatedly absorb water when the equipment is not in use or when it is humid, maintaining a dry environment for the input end 141 and the output end 142.

[0028] Figure 3 This diagram shows a partial cross-sectional view of the flexible circuit board after the packaging structure of the present invention has been connected according to an embodiment of the present invention. Figure 3 For example, Figure 2 The cross-sectional view of the encapsulation structure along section line AA shows a schematic cross-sectional view of the flexible circuit board after the encapsulation structure is connected.

[0029] The flexible circuit board's packaging structure, from bottom to top, consists of a heat sink 170, a flexible substrate 110, a first conductive layer 121, a second conductive layer 122, and a protective layer 130. The flexible substrate 110 is, for example, a PI (Polyimide) film. The first conductive layer 121 is, for example, located on the upper surface of the flexible substrate 110 and is, for example, a copper layer. Through patterning, the first conductive layer 121 can form multiple copper conductive traces (Cu Leads) for electrical connection. The second conductive layer 122 is, for example, located on the first conductive layer 121 and is, for example, a tin-plated layer. It covers the first conductive layer 121 formed by the copper conductive traces and acts as a metal surface treatment layer to prevent the first conductive layer 121 from contacting air and moisture, protecting its conductivity and preventing oxidation. Specifically, the second conductive layer 122 is, for example, formed by tin plating 0.16μm-0.20μm onto the first conductive layer 121 formed by the copper conductive traces. The protective layer 130, for example, is a solder resist layer, disposed on the second conductive layer 122, to provide corresponding insulation properties and protect the first conductive layer 121 and the second conductive layer 122. Of course, the protective layer 130 does not completely cover the entire upper surface of the second conductive layer 122. Specifically, the portion of the second conductive layer 122 used for connection with the chip 160 is exposed from the protective layer 130 to form corresponding inner leads. Furthermore, the leads of the second conductive layer 122 are connected to gold bumps 162 formed on the chip 160, thereby realizing the electrical connection between the chip 160 and the first conductive layer 121 and the fixation of the chip 160 on the flexible substrate 110. Further, to protect the connection position and make the fixation of the chip 160 more secure, a filler adhesive 161 is coated around the chip 160. This filler adhesive 161 can, for example, fill the gap between the chip 160 and the protective layer 130 through capillary action. After curing, the filler adhesive 161 forms a solid support while also providing electrical insulation and physical protection.

[0030] For example, input terminal 141 is used to connect to printed circuit board 200. Specifically, after anisotropic conductive film 143 is pasted on the printed circuit board in advance, the input terminal 141 is aligned with the corresponding area of ​​the printed circuit board 200 and bonded by heating and pressurizing, for example, heating to 150°C-200°C and pressurizing to 1 MPa for 10 seconds. During this process, the flexible substrate 110, the first conductive layer 121, and the second conductive layer 122 in the flexible circuit board packaging structure of the input terminal 141 will experience different degrees of stretching or warping. This will cause gaps 150 to appear at the edges where the input terminal 141, the anisotropic conductive film 143 and the protective layer 130 are connected. These gaps 150 will cause a very small part of the second conductive layer 122 and even the first conductive layer 121 to be exposed to the air. Near the gap 150, a first absorbent layer 151 is provided on the protective layer 130. This first absorbent layer 151 is made of, for example, a superabsorbent polymer material, which can absorb moisture from the surrounding air, keeping the gap 150 in a dry environment. This slows down the oxidation and corrosion of the exposed second conductive layer 122 and the first conductive layer 121, enhancing the product's lifespan and reliability. Similarly, the output terminal 142 is connected to the display bonding pad 301 of the display panel 300. For example, the two are bonded together by applying an anisotropic conductive film 144 to the pad 301 and then applying heat and pressure. A second absorbent layer 152 is provided on the protective layer 130 on one side of the output terminal 142. This second absorbent layer 152 is close to the gap 150 on the output terminal 142 side, keeping the area near the gap 150 on the output terminal 142 side in a dry environment as well.

[0031] Figure 4 This diagram illustrates a display device according to an embodiment of the present invention. The display device includes, for example, a printed circuit board 200, a display panel 300, and an encapsulation structure 100 connecting the printed circuit board 200 and the display panel 300. Specifically, the printed circuit board 200 includes, for example, two components, each of which is connected to the display panel 300 via four encapsulation structures 100 arranged side-by-side. Taking the leftmost encapsulation structure 100 as an example, this encapsulation structure 100 has absorbent layers near the sides connected to the printed circuit board 200 and the display panel 300, respectively, to keep the corresponding areas of the encapsulation structure 100 dry, mitigate potential oxidation and corrosion of the conductive layer, and enhance the product's lifespan and reliability.

[0032] The flexible circuit board packaging structure provided in this embodiment effectively solves the problem of misalignment and warping of the conductive layers at the edges of the input and output terminals, leading to easy oxidation and corrosion, caused by the heating and pressurizing bonding process, by setting a water-absorbing layer near the connection end of the packaging structure. When the flexible circuit board packaging structure is connected to the printed circuit board or display panel under heating and pressurization, the water-absorbing layer can absorb moisture from the surrounding air in a timely manner, preventing it from accumulating near the gaps caused by material deformation, and controlling the ambient humidity near the conductive layer exposed by the gaps within a safe range. In particular, by using a close arrangement of the water-absorbing layer and the connection end with a spacing of no more than 2.5mm, the water absorption range of the polymer water-absorbing material can fully cover the gap area, significantly reducing the risk of accelerated oxidation and corrosion of the conductive layer exposed from the gap due to moisture. At the same time, the heat of the packaging structure during operation will also promote the evaporation of moisture in the water-absorbing layer, allowing the water-absorbing layer to repeatedly absorb moisture when the equipment is not in use or when it is humid, maintaining a dry environment. Especially in high humidity areas, the application of this packaging structure to display devices significantly improves the reliability and service life of the product and effectively reduces the occurrence of related failures.

[0033] The above description does not provide detailed explanations of the technical aspects of the device's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc., of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0034] The embodiments of this utility model have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this utility model. The scope of this utility model is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this utility model, and all such substitutions and modifications should fall within the scope of this utility model.

Claims

1. A packaging structure for a flexible circuit board, characterized in that, include: Flexible substrate; A conductive layer is located on the flexible substrate; A protective layer covering the conductive layer; A connection terminal is located on the conductive layer and protrudes from the protective layer to connect to an external circuit. An absorbent layer is located on the protective layer and adjacent to the connection end; The distance between the absorbent layer and the corresponding connecting end is no greater than 2.5 mm.

2. The packaging structure according to claim 1, characterized in that, The connection terminal includes an input terminal and an output terminal, and both the input terminal and the output terminal include an anisotropic conductive film.

3. The packaging structure according to claim 2, characterized in that, The absorbent layer includes a first absorbent layer and a second absorbent layer, wherein the first absorbent layer is disposed adjacent to the input end and the second absorbent layer is disposed adjacent to the output end.

4. The packaging structure according to claim 3, characterized in that, It also includes a chip disposed on the flexible substrate and electrically connected to the conductive layer.

5. The packaging structure according to claim 4, characterized in that, The chip is also surrounded by insulating filler.

6. The packaging structure according to claim 5, characterized in that, The conductive layer includes a first conductive layer and a second conductive layer, wherein the first conductive layer is disposed on the flexible substrate and the second conductive layer covers the first conductive layer.

7. The packaging structure according to claim 6, characterized in that, The thickness of the second conductive layer is 0.16μm-0.20μm.

8. A display device, characterized in that, include: Display panel; The packaging structure of the flexible circuit board as described in any one of claims 1-7, wherein the output terminal of the packaging structure is connected to the display panel; The circuit board is connected to the input terminal of the package structure.

9. The display device according to claim 8, characterized in that, At least one of the display panel and the circuit board is connected to the packaging structure of the flexible circuit board by heating and pressurizing. The packaging structure of the flexible circuit board has a water-absorbing layer at the corresponding connection end.

Images