KR102017643B1 - Flexible printed circuit boards and fabricating method of the same - Google Patents

Abstract

Provided are a flexible circuit board and a method of manufacturing the same. The flexible circuit board may include a base film having a device mounting portion defined therein, a wiring pattern including at least one conductive wiring extending into the device mounting portion, and a first protective layer exposing the device mounting portion and covering the plurality of conductive wirings. And a second passivation layer formed on the first passivation layer to surround the outside of the boundary of the device mounting portion.

Description

FLEXIBLE PRINTED CIRCUIT BOARDS AND FABRICATING METHOD OF THE SAME

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible circuit board and a method of manufacturing the same, and more particularly to a flexible circuit board including two kinds of protective layers and a method of manufacturing the same.

Recently, according to the trend of miniaturization of electronic devices, chip on film (COF) packaging technology using a flexible circuit board is being used. Flexible circuit boards and COF package technology using the same are used in flat panel displays (FPDs), such as liquid crystal displays (LCDs), organic light emitting diode (OLED) display devices, and the like. do.

In the case of such a flexible circuit board, flux that is scattered from the solder paste used in device mounting may scatter and contaminate the surroundings of the device mounting part. The scattered flux causes the surface modification of the protective layer formed to protect the circuit pattern, and if the surface of the damaged protective layer is exposed to the outside after the flux cleaning, it causes the reliability of the product.

The technical problem to be solved by the present invention is to provide a flexible circuit board comprising two types of protective layers.

Another technical problem to be solved by the present invention is to provide a method for manufacturing a flexible circuit board comprising two types of protective layers.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present disclosure, a flexible circuit board may include a base film having a device mounting portion defined therein, a wiring pattern including at least one conductive wire extending into the device mounting portion, and exposing the device mounting portion. And a first protective layer covering the plurality of conductive wires, and a second protective layer formed on the first protective layer so as to surround an outer side of a boundary of the element mounting portion.

In some embodiments of the present invention, the second protective layer may include a material different from the first protective layer.

In some embodiments of the present invention, the first protective layer may include a soft material, and the second protective layer may include a hard material.

In some embodiments of the present invention, the first protective layer may include a solder resist.

In some embodiments of the present invention, the second protective layer may include at least one material of a polymer and a ceramic.

In some embodiments of the present disclosure, the second protective layer may be formed between the device mounting portion and the first protective layer to surround the device mounting portion.

In some embodiments of the present disclosure, the second protective layer may be formed to extend on the top surface of the first protective layer.

In some embodiments, the second passivation layer is formed on an upper surface of the first passivation layer, the boundary between the first passivation layer and the device mounting portion, the second passivation layer and the device mounting The boundaries between the parts can be the same.

In some embodiments of the present invention, the first protective layer may be formed to be spaced apart from the device mounting part by a width of 0.01 mm to 1 mm in an outward direction thereof.

In some embodiments of the present invention, the second protective layer may be formed to have a width of 0.01 to 2 mm in the outward direction of the device mounting portion.

According to another aspect of the present invention, there is provided a method for manufacturing a flexible circuit board, and providing a base film in which device mounting portions are defined, and forming a wiring pattern extending into the device mounting portion on the base film. And forming a first passivation layer covering the wiring pattern and exposing the device mounting portion, and forming a second passivation layer on the first passivation layer to surround an outer side of a boundary of the device mounting portion.

In some embodiments of the present disclosure, the second protective layer may be formed between the device mounting portion and the first protective layer to surround the device mounting portion.

According to another aspect of the present invention, there is provided a method of manufacturing a flexible circuit board, which provides a base film in which device mounting portions are defined, and forms a wiring pattern extending into the device mounting portion on the base film. And forming a second protective layer so as to surround the outer side of the boundary of the device mounting portion, and forming a first protective layer on the outer side of the second protective layer to cover the wiring pattern.

In some embodiments of the present invention, at least one of the first protective layer or the second protective layer may be formed to overlap the boundary between the sidewalls of the first protective layer and the second protective layer.

In the flexible circuit board according to the embodiments of the present invention, two kinds of protective layers are formed on the circuit pattern, and the protective layer may be damaged during the process of cleaning the flux scattered around the device mounting portion. Defects can be prevented.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a top view of a flexible circuit board in accordance with some embodiments of the present invention.
2 is a cross-sectional view of a flexible circuit board in accordance with some embodiments of the present disclosure, taken along the line AA ′ of FIG. 1.
FIG. 2A is an enlarged view of a portion I of FIG. 1.
FIG. 2B is a cross-sectional view taken along line AA ′ of FIG. 3A.
3 and 4 are cross-sectional views of a flexible circuit board in accordance with some other embodiments of the present invention, taken along the line AA ′ of FIG. 1.
5 to 6 are intermediate step views for explaining a method of manufacturing a flexible circuit board according to some embodiments of the present invention.
7 to 8 are views for explaining the effect of the device mounted on the flexible circuit board according to some embodiments of the present invention.
9 is a diagram of an electronic device that may include a flexible circuit board according to some embodiments of the present disclosure.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. The size and relative size of the components shown in the drawings may be exaggerated for clarity of explanation. Like reference numerals refer to like elements throughout the specification, and "and / or" includes each and every combination of one or more of the mentioned items.

When elements or layers are referred to as "on" or "on" of another element or layer, intervening other elements or layers as well as intervening another layer or element in between. It includes everything. On the other hand, when a device is referred to as "directly on" or "directly on" indicates that no device or layer is intervened in the middle.

The spatially relative terms " below ", " beneath ", " lower ", " above ", " upper " It may be used to easily describe the correlation of a device or components with other devices or components. Spatially relative terms are to be understood as including terms in different directions of the device in use or operation in addition to the directions shown in the figures. For example, when flipping a device shown in the figure, a device described as "below" or "beneath" of another device may be placed "above" of another device. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can also be oriented in other directions, so that spatially relative terms can be interpreted according to orientation.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, "comprises" and / or "comprising" does not exclude the presence or addition of one or more other components in addition to the mentioned components.

Although the first, second, etc. are used to describe various elements or components, these elements or components are of course not limited by these terms. These terms are only used to distinguish one element or component from another element or component. Therefore, the first device or component mentioned below may be a second device or component within the technical idea of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. In addition, the terms defined in the commonly used dictionaries are not ideally or excessively interpreted unless they are specifically defined clearly.

Hereinafter, a flexible circuit board according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 9.

1 is a top view of a flexible circuit board in accordance with some embodiments of the present invention, and FIG. 2 is a cross-sectional view of the flexible circuit board in accordance with some embodiments of the present invention, taken along the line AA ′ of FIG. 1.

1 and 2, a flexible circuit board according to some embodiments of the present invention includes a base film 10, a wiring pattern 20, a first protective layer 30, and a second protective layer 40. can do.

The base film 10 may be formed of a flexible material and may be included as a substrate in the flexible circuit board to bend or fold the flexible circuit board. The base film 10 may be, for example, a polyimide film. Alternatively, the base film 10 may be an insulating film such as polyethylene terephthalate (PET) film, polyethylene naphthalate film, polycarbonate film, or a metal foil such as aluminum oxide foil. In the flexible circuit board according to the embodiment of the present invention, the base film 10 is described as being a polyimide film.

In the base film 10, the device mounting unit 100 may be defined. The device mounting unit 100 may be an area in which electronic component devices including a semiconductor device and a passive device are mounted on a flexible circuit board according to some embodiments of the present invention.

That is, when the device is mounted on the base film 10, the device mounting unit 100 may be a region on the base film 10 that vertically overlaps with the device.

Here, the device mounting part 100 may be formed in plural on the base film 10, and may be formed by separating the semiconductor device mounting part and the passive device mounting part.

The wiring pattern 20 may be formed on the base film 10. The wiring pattern 20 may include at least one conductive wiring formed on the base film 10 and extending into the device mounting unit 100.

The wiring pattern 20 extending into the device mounting unit 100 may function as a terminal in electrical contact with a device mounted on the device mounting unit 100. That is, a solder may be formed on the wiring pattern 20 in the device mounting unit 100, and the device may be mounted in contact with the solder to electrically connect the flexible circuit board and the device.

The wiring pattern 20 may include, for example, a conductive material such as copper, but the present invention is not limited thereto. In detail, the wiring pattern 20 may include a material having electrical conductivity such as gold and aluminum.

The plurality of conductive wires included in the wiring pattern 20 may be spaced apart from each other in the width direction (left and right directions in FIG. 1) of the device mounting unit 100. 1, the plurality of conductive wires may extend in a direction other than the length direction (up and down direction in FIG. 1) of the device mounting unit 100.

In FIG. 1, six wiring patterns 20 are disposed on one side of the device mounting unit 100, but the present invention is not limited thereto. It is apparent that the number of wiring patterns 20 can be changed as much as the design of the flexible circuit board and the device connected thereto.

In addition, although the wiring patterns 20 are respectively disposed on both sides of the device mounting unit 100 in FIG. 1, the present invention is not limited thereto. The wiring pattern 20 may be disposed only on one side of the device mounting unit 100 or in a plurality of arrays.

Although not specifically illustrated in FIG. 1 or FIG. 2, an additional plating layer may be formed on the wiring pattern 20. The plating layer may include tin or gold, for example, to cover the surface of the wiring pattern 20 to protect the wiring pattern 20, and to improve bonding with an element connected on the wiring pattern 20.

The first protective layer 30 may cover the surface of the wiring pattern 20. In detail, the first passivation layer 30 may cover the top and side surfaces of the wiring pattern 20. The first protective layer 30 is formed to cover the surfaces of the base film 10 and the wiring pattern 20, and the wires extending into the device mounting part 100 and the device mounting part 100 of the base film 10. The pattern 20 can be exposed.

However, an area in which the first protective layer 30 covers the surface of the base film 10 may not exactly match an area not defined by the device mounting part 100 of the base film 10. In detail, the first protective layer 30 may be formed to be spaced apart from the device mounting portion 100 of the base film 10 by at least a first distance D1 in an outward direction thereof. Therefore, the first protective layer 30 may expose the device mounting unit 100 and the virtual region surrounding the outer circumference of the device mounting unit 100. The first distance D1 may be, for example, 0.01 mm to 1 mm.

The first protective layer 30 may include, for example, a flexible nonconducting material, and may include, for example, a solder resist.

The second protective layer 40 may be formed on the first protective layer 30. In detail, the second passivation layer 40 may be formed on the first passivation layer 30 to surround the outside of the boundary of the device mounting unit 100.

Herein, the second protective layer 40 formed on the first protective layer 30 may mean that the second protective layer 40 is formed on the side surface and / or the upper surface of the first protective layer 30. However, in some embodiments of the present disclosure, the second protective layer 40 may not overlap the boundary of the device mounting unit 100. That is, the second passivation layer 40 may be formed to be spaced apart by at least a first distance D1 in the boundary of the device mounting unit 100 and its outward direction. As described above, the first distance D1 may be, for example, 0.01 mm to 2 mm.

The second protective layer 40 may be formed to have a first width W1 in the outward direction of the device mounting unit 100. The first width W1 may be, for example, within 0.01 mm to 1 mm.

2 to 4, it is shown that the second protective layer 40 is formed in different shapes.

First, in FIG. 2, the second protective layer 40 may be formed on sidewalls of the first protective layer 30 on both sides of the device mounting unit 100. In this case, the second protective layer 40 may be interposed between the sidewall of the first protective layer 30 and the boundary of the device mounting unit 100. Therefore, the second protective layer 40 may surround the outside of the boundary of the device mounting unit 100. In the flexible circuit board illustrated in FIG. 2, the second protective layer 40 may not cover the top surface of the first protective layer 30. The trench 110 may be defined by the side surface of the second protective layer 40, the base film 10, and the upper surface of the wiring pattern 20, and a device may be mounted in the trench 110.

In some embodiments of the present invention, the first protective layer 30 and the second protective layer 40 partially overlap at the boundary 35 of the sidewalls of the first protective layer 30 and the second protective layer 40. It may be formed. In particular, when the first protective layer 30 and the second protective layer 40 are formed through a printing method, a phenomenon in which the ink of the solder resist spreads at the boundary portions of the protective layers 30 and 40 may occur. The first passivation layer 30 and / or the second passivation layer 40 may be formed to cover the boundary part 35. As a result, the first and second protective layers 30 and 40 may overlap each other, thereby forming a protective layer having a desired thickness.

3 and 4 are cross-sectional views of a flexible circuit board in accordance with some other embodiments of the present invention, taken along the line AA ′ of FIG. 1.

Referring to FIG. 3, the second passivation layer 140 may be formed to cover the side surface of the first passivation layer 30 and extend on the top surface of the first passivation layer 30. Accordingly, the second passivation layer 140 may be conformally formed along the profile of the side and top surfaces of the first passivation layer 30.

The second protective layer 140 may be formed to have the first width W1 in the outward direction of the device mounting unit 100. Therefore, at least a part of the second protective layer 140 may be interposed between the first protective layer 30 and the device mounting unit 100.

Referring to FIG. 4, the second protective layer 240 may cover only the top surface of the first protective layer 30. The second passivation layer 240 may be formed to have a first width W1 in the outward direction of the device mounting unit 100 on the upper surface of the first passivation layer 30.

In some embodiments of the present invention, the boundary defined by the side of the first passivation layer 30 and the boundary defined by the side of the second passivation layer 240 may be the same.

The trench 110 is defined by the side surfaces of the second passivation layer 240 and the first passivation layer 30, the base film 10, and the wiring pattern 20, and a device is formed inside the trench 110. Can be mounted.

Referring back to FIG. 2, the second passivation layer 40 may include, for example, a material different from the first passivation layer 30. The second protective layer 40 may include a material that is resistant to the flux material scattered on the base film 10, and specifically, the second protective layer 40 may include at least one material of a polymer and a ceramic. can do.

In some embodiments of the present invention, the second protective layer 40 and the first protective layer 30 may include the same material, and thus the second protective layer 40 may include a solder resist, Specifically, it may be a hard solder resist.

5 to 6 are intermediate step views for explaining a method of manufacturing a flexible circuit board according to some embodiments of the present invention.

First, referring to FIG. 5, the device mounting unit 100 provides a defined base film 10 and forms a wiring pattern 20 extending into the device mounting unit 100 of the base film 10. The wiring pattern 20 may include, for example, at least one conductive material of copper, gold, or aluminum.

Forming the wiring pattern 20 is a photoetching method for patterning by etching and patterning a metal foil layer formed on one surface of the base film 10, or forming a resist pattern on the base film 10, the base layer is formed, After the electroplating of the conductive material between the resist pattern, the semi-additive method of forming the wiring pattern 20 by removing the resist pattern and the underlying layer, or by printing a conductive paste to print the wiring pattern 20 Manner and the like.

Referring to FIG. 6, the first protective layer 30 is formed to cover the base film 10 and the wiring pattern 20. The first passivation layer 30 may be formed to surround the boundary of the device mounting unit 100 defined in the base film 10. The first passivation layer 30 may be formed to be spaced apart from the boundary of the device mounting unit 100 at a predetermined interval.

The first protective layer 30 may be formed by forming a liquid material such as a solder resist by a printing method or a coating method, or by forming a cover film by a laminating method.

2, a second protective layer 40 is formed on the side surface of the first protective layer 30. The second protective layer 40 may be formed between the side surface of the first protective layer 30 and the device mounting unit 100.

Forming the second protective layer 40 may also be to form a liquid material such as solder resist by a printing method or a coating method, or a cover film by a laminating method, similar to the first protective layer 30. .

Alternatively, when the first protective layer 30 or the second protective layer 40 includes a photosensitive solder resist, the first protective layer is applied after the photosensitive material is applied onto the base film 10 and the wiring pattern 20. It may include forming the first protective layer 30 or the second protective layer 40 by exposing and developing in the shape of the 30 or the second protective layer 40.

On the other hand, it is apparent that the first protective layer 30 can be formed after the second protective layer 40 is first formed according to the manufacturing method. That is, the second protective layer 40 is formed to surround the outer side of the boundary of the element mounting unit 100, and the first protective layer 30 to cover the wiring pattern 20 on the outer side of the second protective layer 40. ) May be formed. Here, the outer side of the second protective layer 40 may mean the opposite side of the inner side when the opposing surface of the second protective layer 40 and the element mounting portion 100 is inward.

5 to 6, the method of manufacturing the flexible circuit board of FIG. 2 has been described, but the present invention is not limited thereto. That is, in the flexible circuit board of FIG. 3, the first protective layer 30 is formed to be spaced apart from the first distance D1 to surround the device mounting unit 100, and the side surface of the first protective layer 30 and The second passivation layer 140 may be formed on the upper surface to have the first width W1 in the outer direction of the device mounting unit 100.

Alternatively, in the flexible circuit board of FIG. 4, the first protective layer 30 is formed to be spaced apart from the first distance D1 to surround the device mounting unit 100, and only the upper surface of the first protective layer 30 is formed. The second protective layer 240 may be formed to cover the second protective layer 240.

In some embodiments of the present invention, the second protective layer 40 described with reference to FIG. 2 and the second protective layers 140 and 240 described with reference to FIG. 3 or FIG. 4 may be integrally formed.

7 to 8 are views for explaining the effect of the device mounted on the flexible circuit board according to some embodiments of the present invention.

First, the relationship between the flux and the first protective layer will be described. It is assumed that the first protective layer 30 on which the second protective layer 40 is not formed is formed up to the vicinity of the device mounting unit 100. The solder 410 is disposed on the wiring pattern 20 on the device mounting unit 100 by printing or dispensing, and the device 400 is mounted so that the arrangement of the terminals of the device 400 and the solder 410 match. Afterwards, a curing process, for example, through reflow, is performed to fix the position of the device 400.

When the flux 500 included in the solder 410 is scattered from the solder 410 and diffused into the peripheral area, the flux 500 may be attached to the first protective layer 30 near the device mounting unit 100. The flux 500 reacts with the first passivation layer 30 to generate a modification of the surface of the first passivation layer 30, and then when the flux 500 is removed with the cleaning liquid in the cleaning step of removing the flux 500. The first passivation layer 30, which is deformed on the surface due to the flux furnace 500, may be exposed. As described above, the deformation of the first protective layer 30 may be a factor of lowering product reliability.

Referring to FIG. 7, in a flexible circuit board according to some embodiments of the present disclosure, a hardening process through reflow is performed, and the flux 500 scattered from the solder 410 is formed at the boundary of the device mount 500. It may be attached to the surface of the second protective layer 40 surrounding the outside.

Referring to FIG. 8, even if the process is performed using the cleaning liquid C to remove the flux 500, since the flux is formed only on the second protective layer 40, the first protective layer 30 is not affected. The flux can be removed without. The washing liquid (C) may include an alcohol solution or an ethyl solution.

In the flexible circuit board according to some embodiments of the present invention, the second protective layer 40 may be formed on the first protective layer 30. That is, the second protective layer 40 may protect the surface of the first protective layer 30 from the flux 500. In the flexible circuit board according to some embodiments of the present invention, the second passivation layer 40 is formed on the first passivation layer so as to surround the outside of the boundary of the device mount 100, thereby surrounding the device mount 100. The first protective layer 30 may be protected from the flux 500.

In addition, the device mounting unit 100 and the first protective layer 30, or the device mounting unit 100 and the second protective layer 40 may be spaced apart by the first distance D1. The cleaning liquid C may be introduced into the gap of the first distance D1, and the flux 500 between the device 400 and the base film 10 may be effectively removed.

9 is a diagram of an electronic device that may include a flexible circuit board according to some embodiments of the present disclosure.

Referring to FIG. 9, an electronic device according to an embodiment of the present invention may include a flexible circuit board 1000, a first external device 1100, a second external device 1200, and a device 400.

The flexible circuit board 1000 may be a flexible circuit board according to some embodiments of the present invention described above with reference to FIGS. 1 to 8. The device 400 may be mounted on the flexible circuit board 1000.

The flexible circuit board 1000 may include non-bending regions NB1 and NB2 and a bending region B disposed between the non-bending regions NB1 and NB2. As illustrated in FIG. 9, the bending area B may be a portion that is bent and mounted when the flexible circuit board 1000 is included in the electronic device.

The flexible circuit board according to some embodiments of the present invention described with reference to FIGS. 1 to 4 may also include a bending area B. FIG. In some embodiments of the present invention, the first protective layer 30 may be formed on the bending area B. FIG. On the contrary, the second protective layer 40 may not be formed on the bending area B. FIG. In addition, the device mounting unit 100 may not be defined on the bending area B. FIG.

That is, the first passivation layer 30 formed at the portion requiring bending property may be formed of a soft material, and the second passivation layer 40 formed at the portion not requiring bending property may be formed of a hard material. have.

The first external device 1100 and the second external device 1200 may be electrically connected by the flexible circuit board 1000. The first external device 1100 may be, for example, a display panel displaying an image, and the second external device 1200 may be an electronic device that provides an output signal to the display panel, but the present invention is limited thereto. It is not.

In the present exemplary embodiment, the first external device 1100 and the second external device 1200 are described as being connected to the same surface of the flexible circuit board 1000, but the first external device 1100 and the second external device 1200 are described. May be connected to different surfaces of the flexible circuit board 1000.

When the first external device 200 is a display panel, the device 400 may be, for example, a display driver IC (DDIC) for driving the display panel.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments but may be manufactured in various forms, and having ordinary skill in the art to which the present invention pertains. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

10: base film 20: wiring pattern
30: first protective layer 40, 140, 240: second second protective layer
100: device mounting unit 400: device
500: flux 1000: flexible circuit board
1100: 1200: external device

Claims (14)

A base film in which device mounting portions are defined;
A wiring pattern including at least one conductive wiring extending into the device mounting portion;
A first protective layer exposing the device mounting portion and covering the wiring pattern; And
And a second protective layer formed on a portion of the side surface and the upper surface of the first protective layer so as to surround the outside of the boundary of the device mounting portion. The method of claim 1,
The second protective layer includes a material different from the first protective layer. The method of claim 2,
The first protective layer includes a flexible material, and the second protective layer includes a rigid material. The method of claim 3, wherein
The first protective layer includes a solder resist. The method of claim 4, wherein
The second protective layer includes at least one material of a polymer and a ceramic. The method of claim 1,
The second protective layer is formed between the element mounting portion and the first protective layer to surround the element mounting portion. delete delete The method of claim 1,
The first protective layer is formed to be spaced apart from the device mounting portion in a width of 0.01mm to 1mm in the outward direction. The method of claim 1,
The second protective layer is formed to have a width of 0.01mm to 2mm in the outer direction of the device mounting portion. Providing a base film with a defined device mount,
Forming a wiring pattern extending on the base film into the device mounting portion,
Forming a first protective layer covering the wiring pattern and exposing the device mounting portion;
A method of manufacturing a flexible circuit board comprising forming a second protective layer on a side of the first protective layer and a part of an upper surface thereof so as to surround an outer side of a boundary of the element mounting portion. The method of claim 11,
And the second protective layer is formed between the element mounting portion and the first protective layer to surround the element mounting portion. delete A base film in which device mounting portions are defined;
A wiring pattern including at least one conductive wiring extending into the device mounting portion;
A first protective layer exposing the device mounting portion and covering the wiring pattern; And
And a second passivation layer formed on a portion of the upper surface of the first passivation layer so as to surround the outside of the boundary of the device mounting portion.

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