Anti-corrosion FPC binding structure and display module binding structure comprising same

Abstract

The utility model relates to an anti-corrosion FPC (Flexible Printed Circuit) binding structure and a display module binding structure comprising the same. The anti-corrosion FPC binding structure comprises a flexible circuit board substrate layer, a copper layer circuit arranged on the substrate layer and a covering film layer covering the copper layer circuit, wherein a golden finger area is formed at the tail end of the copper layer circuit; the extension length L1 of the base material layer at the binding end is 0.1-0.5 mm greater than the extension length L2 of the golden finger of the copper layer circuit; the cover film layer comprises a cover film body and an adhesive layer, and the total extension length L3 of the cover film layer is 0.15-0.6 mm larger than the length L2 of the golden finger of the copper layer, so that a stepped protection structure is formed; the extension length difference of the base material layer and the covering film layer forms a buffer transition area, and the width of the transition area is 0.05-0.2 mm; after the structure is bound, the glue overflowing front edge of the ACF glue completely covers the side edge of the copper layer golden finger and extends to the surface of the buffer transition area. According to the scheme, on the basis that the binding position protection glue is not coated, the narrow frame requirement is met, and the probability of corrosion failure of the binding position in the salt spray test can be reduced.

Description

Technical Field

[0001] This utility model relates to the field of bonding technology, and more specifically, to an anti-corrosion FPC bonding structure and a display module bonding structure including the same. Background Technology

[0002] In recent years, the bezel design of LCD and AMOLED displays has become smaller and smaller, which has made the FPC bonding position of the display glass narrower and narrower. This has increased the challenges to bonding technology, especially since there is not enough space for applying protective adhesive after bonding. This makes the display very susceptible to corrosion failure at the bonding site during salt spray testing. Utility Model Content

[0003] The purpose of this invention is to propose an anti-corrosion FPC bonding structure and a display module bonding structure containing the same, which can meet the requirements of narrow bezels and reduce the probability of bonding failure during salt spray testing without applying protective adhesive to the bonding positions.

[0004] Specifically, the technical solution of this utility model is as follows: a corrosion-resistant FPC bonding structure is proposed, comprising: a flexible circuit board substrate layer, copper layer circuits disposed on the back of the substrate layer, and a cover film layer disposed on the front of the substrate layer, wherein the ends of the copper layer circuits form gold finger areas; the extension length L1 of the substrate layer at the bonding end is 0.1-0.5 mm greater than the extension length L2 of the copper layer circuit gold fingers; the cover film layer comprises a cover film body and an adhesive layer, and the total extension length L3 of the cover film layer is 0.15-0.6 mm greater than the length L2 of the copper layer gold fingers, forming a stepped protective structure; the difference in extension length between the substrate layer and the cover film layer forms a buffer transition area, the width of which is 0.05-0.2 mm; after bonding, the overflow front edge of the ACF adhesive completely covers the side of the copper layer gold fingers and extends to the surface of the buffer transition area.

[0005] As a preferred technical solution, the substrate layer is made of polyimide material with a thickness of 12.5-50μm; the cover film body is a modified epoxy resin composite film with a thickness of 15-30μm; the adhesive layer is an acrylic thermosetting adhesive with a thickness of 10-25μm; and the difference between the extension length L1 of the substrate layer and the length L2 of the copper layer gold finger is 0.2±0.05mm.

[0006] As a preferred technical solution, the cover film adopts a multi-segment laminated structure, including a first cover film segment and a second cover film segment, wherein the first cover film segment extends to the end of the copper layer gold finger, and the second cover film segment extends beyond the end of the copper layer gold finger by 0.15-0.3mm.

[0007] As a preferred technical solution, a gradient bonding interface is formed between the first covering film segment and the second covering film segment, with a bonding angle of 30-60 degrees.

[0008] As a preferred technical solution, the ACF adhesive contains conductive particles with a particle size of 3-8μm, and the volume ratio of conductive particles is 5-15%; the width W1 of the ACF adhesive overflow on the side after curing is 0.15-0.35mm, the overflow thickness H1 is 8-25μm, and the viscosity at 25℃ is 5000-15000cps.

[0009] As a preferred technical solution, the side of the copper layer gold finger is provided with a micro-groove structure, the groove depth is 10-30% of the copper layer thickness, and the width is 5-15μm; the overflow of ACF adhesive fills the micro-groove to form a mechanical anchoring structure.

[0010] As a preferred technical solution, the end of the cover film layer is formed with a bevel angle of 45-75 degrees; the horizontal distance D1 between the vertex of the bevel angle and the end of the copper layer gold finger is 0.05-0.15 mm.

[0011] As a preferred technical solution, the surface of the buffer transition zone is plasma-treated to form a rough surface with a surface roughness Ra of 0.5-2.0 μm; the wetting angle of the ACF adhesive overflow on the rough surface is less than 30 degrees.

[0012] As a preferred technical solution, the structure's protective performance in salt spray testing meets the following requirements: after continuous spraying for 48 hours at a temperature of 35±2℃ and a 5% NaCl solution concentration, the corrosion area rate on the side of the copper layer gold finger is less than 5%.

[0013] On the other hand, a display module binding structure is proposed, comprising:

[0014] A glass substrate for a display screen, the surface of which is provided with bonding electrodes;

[0015] And the corrosion-resistant FPC bonding structure as described above;

[0016] Anisotropic conductive adhesive film electrically connects the gold fingers of the FPC bonding structure to the display bonding electrodes;

[0017] Among them, the overflow edge of the ACF adhesive completely covers the side of the gold finger and extends to the surface of the buffer transition area by 0.05-0.2mm;

[0018] The distance S1 between the edge of the display glass substrate and the end of the FPC substrate layer is 0.15-0.4mm, forming a narrow bezel structure.

[0019] The beneficial effects of this invention are: without applying a bonding protective adhesive, it meets the requirements for narrow bezels while reducing the probability of bonding corrosion failure during salt spray testing. Furthermore, by employing a multi-segment laminated structure for the cover film, the edge protection effect is enhanced. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of an anti-corrosion FPC bonding structure proposed in an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached drawings: 1. Flexible circuit board; 11. Substrate layer; 12. Copper layer circuit; 13. Cover film layer; 131. Cover film body; 132. Adhesive layer; 133. First cover film segment; 134. Second cover film segment; 2. Groove structure; 3. Beveled angle; 4. Glass substrate; 5. ACF adhesive; 6. Excess adhesive. Detailed Implementation

[0023] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0024] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0025] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0026] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0027] It should be noted that "multiple" as mentioned in this article refers to two or more.

[0028] Example

[0029] like Figure 1 As shown, this embodiment proposes an anti-corrosion FPC bonding structure, including: a flexible circuit board 1 substrate layer 11, copper layer circuits 12 disposed on the back of the substrate layer 11, and a cover film layer 13 disposed on the front of the substrate layer 11. The ends of the copper layer circuits 12 form gold finger areas. The extension length L1 of the substrate layer 11 at the bonding end is 0.1-0.5 mm greater than the extension length L2 of the copper layer circuits 12 gold fingers. The cover film layer 13 includes a cover film body 131 and an adhesive layer 132. The total extension length L3 of the cover film layer 13 is 0.15-0.6 mm greater than the length L2 of the copper layer gold fingers, forming a stepped protective structure. The difference in extension length between the substrate layer 11 and the cover film layer 13 forms a buffer transition area with a width of 0.05-0.2 mm. After bonding, the overflow adhesive 6 of the ACF adhesive 5 completely covers the side of the copper layer gold fingers and extends to the surface of the buffer transition area.

[0030] Preferably, the substrate layer 11 is made of polyimide material with a thickness of 12.5-50μm; the cover film body 131 is a modified epoxy resin composite film with a thickness of 15-30μm; the adhesive layer 132 is an acrylic thermosetting adhesive with a thickness of 10-25μm; and the difference between the extension length L1 of the substrate layer 11 and the length L2 of the copper layer gold finger is 0.2±0.05mm.

[0031] Preferably, the cover film layer 13 adopts a multi-segment laminated structure, including a first cover film segment 133 and a second cover film segment 134, wherein the first cover film segment 133 extends to the end of the copper layer gold finger, and the second cover film segment 134 extends beyond the end of the copper layer gold finger by 0.15-0.3mm; a gradient bonding interface is formed between the two cover film segments, and the bonding angle is 30-60 degrees. The introduction of the multi-segment laminated structure of the cover film layer 13 enhances the edge protection effect.

[0032] Preferably, not shown in the figure, the substrate layer 11 may also have a reinforcing layer at the bonding end. The reinforcing layer is made of stainless steel or FR4 and has a thickness of 0.1-0.3 mm. The distance between the end of the reinforcing layer and the end of the copper layer gold finger is 0.05-0.15 mm, forming a secondary buffer transition zone. This improvement, combined with existing FPC reinforcement schemes, ensures structural reliability.

[0033] Preferably, the ACF adhesive 5 contains conductive particles with a particle size of 3-8μm, and the volume percentage of conductive particles is 5-15%; the width W1 of the overflow adhesive 6 on the side of the cured ACF adhesive 5 is 0.15-0.35mm, the thickness H1 of the overflow adhesive 6 is 8-25μm, and the viscosity at 25℃ is 5000-15000cps.

[0034] Preferably, the copper layer gold fingers have a microgroove structure 2 on their side, with a groove depth of 10-30% of the copper layer thickness and a width of 5-15μm; ACF adhesive 5 overflows 6 to fill the microgroove to form a mechanical anchoring structure, thus strengthening the fixation.

[0035] Preferably, the end of the covering film layer 13 forms a chamfer angle 3, which is 45-75 degrees; the horizontal distance D1 between the vertex of the chamfer angle 3 and the end of the copper layer gold finger is 0.05-0.15 mm.

[0036] Preferably, the surface of the buffer transition zone is plasma-treated to form a rough surface with a surface roughness Ra of 0.5-2.0 μm; the wetting angle of the ACF adhesive 5 overflow 6 on the rough surface is less than 30 degrees. Plasma treatment improves the adhesion of the adhesive layers.

[0037] Preferably, the protective performance of the structure in the salt spray test meets the following requirements: after continuous spraying for 48 hours at a temperature of 35±2℃ and a NaCl solution concentration of 5%, the corrosion area rate on the side of the copper layer gold finger is less than 5%.

[0038] On the other hand, this embodiment also proposes a display module binding structure, comprising:

[0039] The display glass substrate 4 has bonding electrodes on its surface;

[0040] And the corrosion-resistant FPC bonding structure as described above;

[0041] Anisotropic conductive adhesive film electrically connects the gold fingers of the FPC bonding structure to the display bonding electrodes;

[0042] Among them, the leading edge of ACF glue 5 (overflow glue 6) completely covers the side of the gold finger and extends to the surface of the buffer transition area by 0.05-0.2mm;

[0043] The distance S1 between the edge of the display glass substrate 4 and the end of the FPC substrate layer 11 is 0.15-0.4mm, forming a narrow bezel structure.

[0044] This patented technology, without applying a protective adhesive to the bonding points, not only meets the requirements for narrow bezels but also reduces the probability of bonding point corrosion failure during salt spray testing.

[0045] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A corrosion-resistant FPC bonding structure, characterized in that, include: The flexible circuit board has a substrate layer, copper layer circuitry disposed on the back side of the substrate layer, and a cover film layer disposed on the front side of the substrate layer, wherein the ends of the copper layer circuitry form gold finger areas. The extension length L1 of the substrate layer at the bonding end is 0.1-0.5 mm longer than the extension length L2 of the copper layer gold finger; the cover film layer includes a cover film body and an adhesive layer, and the total extension length L3 of the cover film layer is 0.15-0.6 mm longer than the length L2 of the copper layer gold finger, forming a stepped protective structure; the difference in extension length between the substrate layer and the cover film layer forms a buffer transition zone with a width of 0.05-0.2 mm; after bonding, the overflow front of the ACF adhesive completely covers the side of the copper layer gold finger and extends to the surface of the buffer transition zone.

2. The corrosion-resistant FPC bonding structure according to claim 1, characterized by, The substrate layer is made of polyimide material with a thickness of 12.5-50 μm; the cover film body is a modified epoxy resin composite film with a thickness of 15-30 μm; the adhesive layer is an acrylic thermosetting adhesive with a thickness of 10-25 μm; the difference between the extension length L1 of the substrate layer and the length L2 of the copper layer gold finger is 0.2±0.05 mm.

3. The corrosion-resistant FPC bonding structure according to claim 1, characterized by, The cover film adopts a multi-segment laminated structure, including a first cover film segment and a second cover film segment, wherein the first cover film segment extends to the end of the copper layer gold finger, and the second cover film segment extends beyond the end of the copper layer gold finger by 0.15-0.3mm.

4. The corrosion-resistant FPC bonding structure according to claim 3, characterized by, A gradient bonding interface is formed between the first covering film segment and the second covering film segment, with a bonding angle of 30-60 degrees.

5. The corrosion-resistant FPC bonding structure according to claim 1, characterized by, The ACF adhesive contains conductive particles with a particle size of 3-8μm, and the volume percentage of conductive particles is 5-15%. The ACF adhesive has an overflow width W1 of 0.15-0.35mm and an overflow thickness H1 of 8-25μm after curing. The viscosity at 25℃ is 5000-15000cps.

6. The corrosion-resistant FPC bonding structure according to claim 1, wherein, The copper layer gold finger has a micro-groove structure on its side, with a groove depth of 10-30% of the copper layer thickness and a width of 5-15μm; the ACF adhesive overflows and fills the micro-groove to form a mechanical anchoring structure.

7. The corrosion-resistant FPC bonding structure according to claim 1, wherein The end of the cover film layer is formed with a bevel angle of 45-75 degrees; the horizontal distance D1 between the vertex of the bevel angle and the end of the copper layer gold finger is 0.05-0.15 mm.

8. The corrosion-resistant FPC bonding structure according to claim 1, wherein, The surface of the buffer transition zone is formed by plasma treatment to form a rough surface with a surface roughness Ra of 0.5-2.0 μm; the wetting angle of the ACF adhesive overflow on the rough surface is less than 30 degrees.

9. The corrosion-resistant FPC bonding structure according to claim 1, wherein, The structure's protective performance in salt spray testing meets the following requirements: after continuous spraying for 48 hours at a temperature of 35±2℃ and a 5% NaCl solution concentration, the corrosion area rate on the side of the copper layer gold finger is less than 5%.

10. A display module binding structure, characterized by ,Include: A glass substrate for a display screen, the surface of which is provided with bonding electrodes; And the corrosion-resistant FPC bonding structure as described in any one of claims 1-9; Anisotropic conductive adhesive film electrically connects the gold fingers of the FPC bonding structure to the display bonding electrodes; The ACF adhesive overflow front completely covers the side of the gold finger and extends to the surface of the buffer transition area by 0.05-0.2mm; the distance S1 between the edge of the display glass substrate and the end of the FPC substrate layer is 0.15-0.4mm, forming a narrow bezel structure.

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