CN112888154B - Flexible circuit board, preparation method and display device - Google Patents

Abstract

The disclosure provides a flexible circuit board, a preparation method and a display device, belongs to the technical field of display, and can solve the problem that a metal wire in the conventional flexible circuit board is easy to short-circuit in a high-temperature and high-humidity environment. The flexible circuit board of the present disclosure includes: the device comprises a substrate, a plurality of metal wires arranged on the substrate at intervals, and a covering layer positioned on one side of the metal wires away from the substrate; the flexible circuit board is characterized in that the flexible circuit board further comprises: an insulating layer between the metal line and the capping layer; the insulating layer is free of halogen ions and is configured to prevent metal ions in the metal lines from migrating with halogen ions in the capping layer.

Description

Flexible circuit board, preparation method and display device

Technical Field

The disclosure belongs to the technical field of display, and particularly relates to a flexible circuit board, a preparation method and a display device.

Background

Along with the continuous development of display technology, the requirements of users on the use environment of electronic display devices are higher and higher at present, for example, the environments with harsh conditions such as sauna rooms, high-temperature and high-humidity equatorial regions and the like, so that reliability evaluation means become important standards for evaluating the reliability of electronic display devices such as mobile phones and the like, wherein the operation test of the mobile phones is carried out in the environment with the temperature of 85 ℃ and the humidity of 85%, which is a key ring. However, the high temperature and high humidity environment can increase molecular motion and generate vapor, and the flexible circuit board (Flexible Printed Circuit Board, FPC) in the mobile phone can generate various defects under the condition. For example, since the cover layer of the flexible circuit board contains halogen ions with negative charges, the metal wires contain metal ions with positive charges and ions with opposite polarity are attracted to each other, and the ions are transported by taking water vapor as a medium to generate ion migration, metal derivatives are easy to form between adjacent metal wires, and in the long-time ion migration process, a metal ion bridge is formed between the adjacent metal wires to short-circuit the adjacent metal wires together, so that a short-circuit phenomenon is easy to be caused.

Disclosure of Invention

The disclosure aims to at least solve one of the technical problems in the prior art, and provides a flexible circuit board, a preparation method and a display device.

In a first aspect, embodiments of the present disclosure provide a flexible circuit board, including: the device comprises a substrate, a plurality of metal wires arranged on the substrate at intervals, and a covering layer positioned on one side of the metal wires away from the substrate; the flexible circuit board further includes: an insulating layer between the metal line and the capping layer;

the insulating layer is free of halogen ions and is configured to prevent metal ions in the metal line and halogen ions in the capping layer from migrating to each other.

Optionally, the metal wire has a surface facing away from one side of the substrate, and a first side surface and a second side surface perpendicular to the surface and opposite to the first side surface;

the insulating layer covers at least a surface of the metal line, the first side surface, and the second side surface.

Optionally, the material of the insulating layer includes: at least one of silicon nitride or silicon oxide.

Optionally, the material of the metal wire includes: copper.

Optionally, the material of the cover layer includes: polyimide.

Optionally, the extending directions of the metal lines are the same and the intervals between the adjacent metal lines are equal.

Optionally, the flexible circuit board further includes: a shielding layer;

the shielding layer is positioned on one side of the covering layer away from the substrate.

In a second aspect, embodiments of the present disclosure provide a display device including the flexible circuit board provided as described above.

Optionally, the display device further includes: a display panel and a driving chip;

and the signal wires in the display panel are connected with the output end of the driving chip through the metal wires in the flexible circuit board.

In a third aspect, an embodiment of the present disclosure provides a method for manufacturing a flexible circuit board, including:

forming a plurality of metal lines arranged at intervals on a substrate;

forming an insulating layer on one side of the metal wire, which is away from the substrate, by using a physical vapor deposition process or an electroplating process;

and forming a covering layer on one side of the insulating layer, which is away from the substrate.

Drawings

Fig. 1 is a schematic cross-sectional view of an exemplary flexible circuit board;

FIG. 2 is a schematic plan view of an exemplary flexible circuit board;

fig. 3 is a schematic cross-sectional structure of a flexible circuit board according to an embodiment of the disclosure;

fig. 4 is a schematic cross-sectional structure of another flexible circuit board according to an embodiment of the disclosure;

fig. 5 is a schematic flow chart of a method for manufacturing a flexible circuit board according to an embodiment of the disclosure.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present disclosure, the present disclosure will be described in further detail with reference to the accompanying drawings and detailed description.

Unless defined otherwise, technical or scientific terms used in this disclosure should be given the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The terms "first," "second," and the like, as used in this disclosure, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Likewise, the terms "a," "an," or "the" and similar terms do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.

Fig. 1 is a schematic cross-sectional structure of an exemplary flexible circuit board, as shown in fig. 1, including: the substrate 101, a plurality of metal lines 102 spaced apart on the substrate 101, and a cover layer 103 on a side of the metal lines 102 facing away from the substrate 101. The cover layer 103 protects the metal lines 102 and prevents short circuits between adjacent metal lines 102. However, in the practical application process, the signals transmitted by different metal wires 102 are different, so that voltages on adjacent metal wires 102 are different, and water vapor is easily generated in a high-temperature and high-humidity environment, so that the materials of the metal wires 102 and the covering layer 103 are easily electrolyzed, free halogen ions are formed in the covering layer 103 and carry negative charges, and free metal ions are formed in the metal wires 102 and carry positive charges. Ions with opposite polarity charges are attracted to each other, and are transported by using water vapor as a medium to generate ion migration, so that metal derivatives are easy to form between adjacent metal wires 102, and in the long-time ion migration process, a metal ion bridge 104 (the structure of which is shown in fig. 2) is formed between the adjacent metal wires 102, so that the adjacent metal wires 102 are short-circuited together, and a short circuit phenomenon is easy to be caused. In order to at least one of the above technical problems, the embodiments of the present disclosure provide a flexible circuit board, a manufacturing method thereof, and a display device, and the flexible circuit board, the manufacturing method thereof, and the display device provided by the embodiments of the present disclosure are described in further detail below with reference to the accompanying drawings and detailed description.

In a first aspect, an embodiment of the present disclosure provides a flexible circuit board, and fig. 3 is a schematic cross-sectional structure of the flexible circuit board provided in the embodiment of the present disclosure, as shown in fig. 3, where the flexible circuit board includes: a substrate 101, a plurality of metal lines 102 arranged on the substrate 101 at intervals, and a cover layer 103 arranged on one side of the metal lines 102 away from the substrate 101; the flexible circuit board further includes: an insulating layer 105 located between the metal line 102 and the cover layer 103; the insulating layer 105 is free of halogen ions, and the insulating layer 105 is configured to prevent the metal ions in the metal line 102 and the halogen ions in the capping layer 103 from migrating to each other.

In the flexible circuit board provided in the embodiments of the present disclosure, the cover layer 103 generally contains halogen ions due to process and material limitations, and in the embodiments of the present disclosure, an insulating layer 105 is disposed between the metal line 102 and the cover layer 103, and the insulating layer 105 is different from the cover layer 103 in that no halogen ions are contained therein. On the one hand, the insulating layer 105 can tightly encapsulate the metal wire 102, so that the metal wire 102 and the cover layer 103 are isolated from each other, and metal ions in the metal wire 102 and halogen ions in the cover layer 103 are prevented from migrating to each other, so that the free metal ions and the free halogen ions react with each other to form metal derivatives, and a metal ion bridge capable of conducting is prevented from being formed between adjacent metal wires 102, and further the short circuit phenomenon caused by the short circuit of the adjacent metal wires 102 is prevented. On the other hand, the derivative formed by the reaction of the cations generated by ionization and the halogen ions of the insulating layer 105 generally has no conductive effect, so that the short circuit phenomenon between the adjacent metal wires 102 can be avoided, and furthermore, the halogen ions in the insulating layer 103 are easier to attract the cations in the insulating layer 105 compared with the distance between the metal wires 102 and the cover layer 103, so that the metal ions in the metal wires 102 and the halogen ions in the cover layer 103 can be prevented from migrating mutually, and the derivative formed by the cations in the insulating layer 105 and the halogen ions in the cover layer 103 has no conductive effect, so that the short circuit phenomenon caused by the short circuit of the adjacent metal wires 102 can be further avoided.

In some embodiments, as shown in fig. 4, the metal line 102 has a surface 1020 facing away from the side of the substrate 101, and a first side 1021 and a second side 1022 disposed perpendicular to and opposite the surface 1020; the insulating layer 105 covers at least the surface 102, the first side 1021, and the second side 1022 of the metal line 102.

It should be noted that, the metal line 102 is formed on the substrate 101, and has a surface 1020 facing away from the substrate 101, and a first side 1021 and a second side 1022 disposed perpendicular to and opposite to the surface 1020, and the insulating layer 105 may cover the surface 1020, the first side 1021, and the second side 1022 of the metal layer 102, and may also cover the substrate 101 exposed between adjacent metal lines 102. In practical application, the surface 1020 of the metal layer 102, the first side 1021, the second side 1022 and the insulating layer 105 on the substrate 101 exposed between the adjacent metal wires 102 are in an integrated structure, so that the process difficulty can be reduced, the process steps can be reduced, and the preparation cost can be saved.

In some embodiments, the material of insulating layer 105 includes: at least one of silicon nitride or silicon oxide.

The insulating layer 105 may have a single-layer structure or a composite structure, for example, the insulating layer 105 may have a single silicon nitride film layer or a multilayer composite structure in which silicon nitride film layers and silicon oxide film layers are alternately arranged. In the embodiment of the present disclosure, a single-layer structure in which the insulating layer 105 is a silicon nitride film layer will be described. On the one hand, the silicon nitride structure is compact, so that the metal wires 102 can be tightly coated, the metal wires 102 and the covering layer 103 are mutually isolated, and metal ions in the metal wires 102 and halogen ions in the covering layer 103 are prevented from mutually migrating, so that free metal ions and free halogen ions can be prevented from mutually reacting to form metal derivatives, a metal ion bridge which can conduct electricity can be prevented from being formed between adjacent metal wires 102, and further the phenomenon that the adjacent metal wires 102 are in short circuit together to cause short circuit can be prevented. On the other hand, silicon ions Si generated by ionization of the silicon nitride film layer ²⁺ The derivatives formed by reaction with the halogen ions generally do not have a conductive effect, so that the occurrence of adjacent metal lines 102 can be avoidedShort circuit phenomenon, and because the silicon nitride film is closer to the cover layer 103 than the metal wire 102, the halogen ions in the cover layer 103 are easier to attract the silicon ions Si in the silicon nitride film ²⁺ Can prevent the mutual migration of metal ions in the metal line 102 and halogen ions in the cover layer 103, and silicon ions Si in the silicon nitride film layer ²⁺ The silicon ion derivatives formed by reacting with the halogen ions in the capping layer 103 have no conductivity, so that the shorting phenomenon caused by shorting adjacent metal lines 102 can be further avoided. It is understood that the material of the insulating layer 105 may be other insulating layer materials besides silicon nitride and silicon oxide, which are not listed again. In the embodiment of the disclosure, since silicon nitride is a common insulating material for manufacturing the display panel, it is unnecessary to develop a new insulating material, and thus development and manufacturing costs can be reduced.

In some embodiments, the material of the metal line 102 includes: copper.

It should be noted that the material of the metal line 102 may be copper, which has good conductivity and good ductility, and a plating process may be used to form a plurality of copper wires on the substrate 101. It is understood that the material of the metal line 102 may also be other metal materials with good electrical conductivity, for example: silver, and the like. In practice, a preferred material for the metal line 102 is copper for cost reduction.

In some embodiments, the material of the cover layer 103 includes: polyimide.

It should be noted that, the material of the cover layer 103 may be polyimide, so that the flexible circuit board can be ensured to have good bending performance while protecting the metal wire 102. Polyimide film layers are typically attached to the side of the insulating layer 105 facing away from the substrate 101 using an adhesive layer, and may also fill the gaps between adjacent metal lines 102.

In some embodiments, the extending direction of each metal line 102 is the same and the spacing between adjacent metal lines 102 is equal.

It should be noted that, the metal wires 102 may be manufactured by the same process and are uniformly distributed on the substrate 101, and the extending directions of the metal wires 102 are the same and the distances between the adjacent metal wires 102 are equal, so that the process difficulty is reduced and the manufacturing cost is saved.

In some embodiments, the flexible circuit board further comprises: a shielding layer 106; the shielding layer 106 is located on the side of the cover layer 103 facing away from the substrate 101.

It should be noted that, the shielding layer 106 may be an integral film layer made of a metal material, and may shield static electricity generated in the application process, so that interference caused by static electricity release to signals transmitted in the metal wire 102 may be prevented, and defects such as signal transmission errors may be avoided.

In a second aspect, an embodiment of the present disclosure provides a display device including the flexible circuit board provided in any one of the embodiments, the display device further including: a display panel and a driving chip; the signal wires in the display panel are connected with the output ends of the driving chips through metal wires in the flexible circuit board. The display device can be, for example, an electronic device with a display function, such as a mobile phone, a tablet personal computer, an electronic watch, a sports bracelet, a notebook computer and the like. The implementation principle and technical effect of the display device can be referred to the above discussion of the implementation principle and technical effect of the display substrate, and will not be repeated here.

In a third aspect, an embodiment of the present disclosure provides a method for manufacturing a flexible circuit board, and fig. 5 is a schematic flow chart of the method for manufacturing a flexible circuit board provided in the embodiment of the present disclosure, as shown in fig. 5, where the method for manufacturing a flexible circuit board includes the following steps:

s501, forming a plurality of metal lines arranged at intervals on a substrate.

S502, forming an insulating layer on one side of the metal wire, which is away from the substrate, by using a physical vapor deposition process or an electroplating process.

And S503, forming a covering layer on the side of the insulating layer, which faces away from the substrate.

In the method for manufacturing the flexible circuit board provided by the embodiment of the disclosure, copper can be used as a material of the metal wires, and a plurality of metal wires which are arranged at intervals are formed on the substrate by adopting an electroplating process. And then, using silicon nitride as a material of the insulating layer, and forming the insulating layer on one side of the metal wire, which is away from the substrate, by adopting a physical vapor deposition or electroplating process. And forming a covering layer on the side of the insulating layer, which is away from the substrate, by using polyimide as a material of the covering layer so as to protect the metal wires. In the embodiment of the disclosure, the insulating layer may be made by a physical vapor deposition process or an electroplating process, and the thickness thereof is negligible, so as to avoid increasing the thickness of the flexible circuit board. By using the preparation method provided by the embodiment of the present disclosure, a flexible circuit board structure as shown in fig. 3 and fig. 4 may be formed, on one hand, the insulating layer 105 may tightly encapsulate the metal wire 102, so that the metal wire 102 and the cover layer 103 are isolated from each other, and metal ions in the metal wire 102 and halogen ions in the cover layer 103 are prevented from migrating to each other, so that the free metal ions and the free halogen ions react with each other to form metal derivatives, and thus, a metal ion bridge capable of conducting is prevented from being formed between adjacent metal wires 102, and further, a short circuit phenomenon caused by shorting of adjacent metal wires 102 is prevented. On the other hand, the derivative formed by the reaction of the cations generated by ionization and the halogen ions of the insulating layer 105 generally has no conductive effect, so that the short circuit phenomenon between the adjacent metal wires 102 can be avoided, and furthermore, the halogen ions in the insulating layer 103 are easier to attract the cations in the insulating layer 105 compared with the distance between the metal wires 102 and the cover layer 103, so that the metal ions in the metal wires 102 and the halogen ions in the cover layer 103 can be prevented from migrating mutually, and the derivative formed by the cations in the insulating layer 105 and the halogen ions in the cover layer 103 has no conductive effect, so that the short circuit phenomenon caused by the short circuit of the adjacent metal wires 102 can be further avoided.

It is to be understood that the above embodiments are merely exemplary embodiments employed to illustrate the principles of the present disclosure, however, the present disclosure is not limited thereto. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the disclosure, and are also considered to be within the scope of the disclosure.

Claims (7)

1. A flexible wiring board for use in a high temperature and high humidity environment, comprising: the device comprises a substrate, a plurality of metal wires arranged on the substrate at intervals, and a covering layer positioned on one side of the metal wires away from the substrate; the flexible circuit board is characterized by further comprising: an insulating layer between the metal line and the capping layer;

the insulating layer is free of halogen ions and is configured to prevent metal ions in the metal line and halogen ions in the cover layer from migrating to each other;

the metal wire is provided with a surface facing away from one side of the substrate, and a first side surface and a second side surface which are perpendicular to the surface and are oppositely arranged;

the insulating layer covers at least the surface, the first side surface and the second side surface of the metal wire;

ionization of the material of the insulating layer generates silicon ions;

the flexible circuit board further includes: a shielding layer;

the shielding layer is positioned on one side of the covering layer away from the substrate.

2. The flexible circuit board of claim 1 wherein the material of the insulating layer comprises: at least one of silicon nitride or silicon oxide.

3. The flexible circuit board of claim 1 wherein the material of the metal wire comprises: copper.

4. The flexible circuit board of claim 1 wherein the material of the cover layer comprises: polyimide.

5. The flexible wiring board according to claim 1, wherein the extending direction of each of the metal wires is the same and the pitches between the adjacent metal wires are equal.

6. A display device comprising the flexible wiring board according to any one of claims 1 to 5.

7. The display device according to claim 6, wherein the display device further comprises: a display panel and a driving chip;

and the signal wires in the display panel are connected with the output end of the driving chip through the metal wires in the flexible circuit board.

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