Layer structure for improving wrinkles of FPC binding area

Abstract

The invention discloses a layer structure for improving wrinkles in an FPC (flexible printed circuit) binding area, which comprises a basic laminated structure, a binding area is formed by extending parts of a base material layer and a middle copper foil layer in the basic laminated structure, and a reinforcing layer structure is arranged on one side of the extending part of the base material layer in the binding area. And the extended base material layer part is positioned between the extended middle copper foil layer part and the reinforcing layer structure. The layer structure for improving the wrinkles in the FPC binding area is reasonable in design, the strength of the binding area is improved, and the deformation resistance is improved; material selection and thickness optimization of the reinforcing layer reduce thermal expansion difference and balance thermal stress distribution; a binding area is ensured to be flat, poor welding is avoided, and process reliability is improved.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to a layer structure for improving wrinkles in the bonding region of an FPC. Background Technology

[0002] Flexible printed circuit boards (FPCs) are widely used in displays, consumer electronics, and other fields. Their core structure consists of multiple layers of flexible materials (cover layer, adhesive layer, copper foil, substrate, etc.). In FPC manufacturing, the bonding area is a critical part connecting the LCD glass driver chip circuitry, requiring thermoforming to achieve electrical conductivity. However, as... Figure 2 As shown, traditional FPC designs lack structural reinforcement in the bonding area a. During FPC manufacturing, this area is prone to wrinkles (unevenness) under high temperature, pressure, or mechanical stress, which in turn leads to problems such as alignment failure or bonding misalignment when bonding the liquid crystal glass, seriously affecting product yield and even product reliability.

[0003] The existing flexible printed circuit boards have the following main shortcomings: 1. Insufficient structural strength: The bonding area only has basic stacked layers (cover layer + adhesive layer + copper foil + substrate), lacking additional support, and is easily affected by the stress of hot pressing process, resulting in wrinkles; 2. Mismatch in thermal expansion coefficients: Different material layers (such as copper foil and substrate) have large differences in expansion at high temperatures, leading to local warping; 3. Poor process stability: Wrinkles may cause poor solder joints and circuit breakage, with yield loss as high as 5%-10%. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a layer structure that improves the wrinkles in the bonding area of ​​an FPC, thereby increasing the strength of the bonding area and enhancing its resistance to deformation.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: The improved FPC bonding area wrinkle layer structure includes a basic stacked structure, in which the substrate layer and the intermediate copper foil layer in the basic stacked structure extend to form a bonding area, and a reinforcing layer structure is provided on one side of the extended substrate layer portion in the bonding area, with the extended substrate layer portion located between the extended intermediate copper foil layer portion and the reinforcing layer structure.

[0006] Further or preferred: In the basic laminated structure, the upper side of the substrate layer is provided with an upper copper foil layer, an upper adhesive layer and an upper cover layer from the inside to the outside.

[0007] In the basic laminated structure, a lower adhesive layer and a lower cover layer are provided sequentially from the inside to the outside on the lower side of the middle copper foil layer.

[0008] The reinforcing layer structure includes a reinforcing adhesive layer and a reinforcing cover layer, wherein the reinforcing adhesive layer is located between the substrate layer and the reinforcing cover layer.

[0009] The thickness of the reinforcing adhesive layer ranges from 20 to 30 μm.

[0010] The thickness of the reinforcing cover layer ranges from 25 to 50 μm.

[0011] The reinforcing adhesive layer is a modified epoxy resin adhesive layer, and the reinforcing cover layer is a glass fiber reinforced polyimide layer.

[0012] The reinforcing cover layer contains copper foil sheets.

[0013] The copper foil sheet has a mesh structure.

[0014] Compared with the prior art, the present invention has the following advantages: The improved FPC bonding area has a reasonable layer structure design, which increases the strength of the bonding area and enhances its resistance to deformation. The selection and thickness of the reinforcing layer material are optimized to reduce differences in thermal expansion and balance the distribution of thermal stress. The bonding area is ensured to be flat, avoiding poor welding and improving process reliability. Attached Figure Description

[0015] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings: Figure 1 This is a schematic diagram of the layer structure of the present invention.

[0016] Figure 2 This is a schematic diagram of the existing layer structure.

[0017] In the picture: 1. Upper cover layer, 2. Upper adhesive layer, 3. Upper copper foil layer, 4. Lower cover layer, 5. Lower adhesive layer, 6. Substrate layer, 7. Middle copper foil layer, 8. Reinforcing adhesive layer, 9. Reinforcing cover layer. Detailed Implementation

[0018] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and through the description of the examples.

[0019] like Figure 1 As shown, the improved FPC bonding area wrinkle layer structure includes a basic laminate structure, in which the substrate layer 6 and the intermediate copper foil layer 7 extend to form a bonding area a; a reinforcing layer structure is provided on one side of the extended substrate layer portion within the bonding area, and the extended substrate layer portion is located between the extended intermediate copper foil layer portion and the reinforcing layer structure.

[0020] This invention improves the layer structure design of the FPC bonding area by making the bonding area more reasonable, increasing the strength of the bonding area and improving the resistance to deformation; optimizing the selection and thickness of the reinforcing layer material reduces the difference in thermal expansion and balances the distribution of thermal stress; ensuring the bonding area is flat, avoiding poor welding, and improving the reliability of the process.

[0021] In the basic laminated structure, the upper side of the substrate layer 6 is provided with an upper copper foil layer 3, an upper adhesive layer 2 and an upper cover layer 1 from the inside to the outside; the lower side of the middle copper foil layer 7 is provided with a lower adhesive layer 5 and a lower cover layer 4 from the inside to the outside.

[0022] The upper and lower cover layers protect the circuitry, with a thickness ranging from 12-25 μm, and are resistant to high temperatures and chemical corrosion. The upper and lower adhesive layers bond the layers together, with a thickness ranging from 10-20 μm and high bonding strength. The individual copper foil layers are used for conductive circuitry, with a thickness of 9-35 μm and an etching precision of ±5 μm. The substrate layer provides flexible support, with a thickness of 25-50 μm and is resistant to bending.

[0023] Preferably, the reinforcing layer structure includes a reinforcing adhesive layer 8 and a reinforcing cover layer 9, with the reinforcing adhesive layer located between the substrate layer and the reinforcing cover layer; this increases the strength of the bonding area and improves the resistance to deformation.

[0024] The thickness of the reinforcing adhesive layer ranges from 20 to 30 μm; the thickness of the reinforcing capping layer ranges from 25 to 50 μm. The reinforcing adhesive layer is a modified epoxy resin adhesive layer, and the reinforcing capping layer is a glass fiber reinforced polyimide layer.

[0025] Furthermore, a reinforcing adhesive layer, 15-25 μm thick, is made of high-modulus adhesive (such as modified epoxy resin) to improve local bond strength. A reinforcing cover layer, 30-40 μm thick, is made of high-rigidity materials (such as glass fiber reinforced polyimide) to provide mechanical support.

[0026] Furthermore, the reinforcing cover layer is wrapped with copper foil. Preferably, the copper foil has a mesh structure, which is lightweight, and the glass fiber reinforced polyimide is incorporated into the mesh, ensuring a reliable bond. The built-in copper foil mesh further enhances the structural strength of the bonding area, making it less prone to deformation.

[0027] The reinforcing layer is bonded to the base layer via an adhesive layer, and the cover layer is located on the outermost layer, forming a "sandwich" structure (cover layer - adhesive layer - copper foil - substrate - copper foil - adhesive layer - cover layer - reinforcing adhesive layer - reinforcing cover layer); the reinforcing layer only covers the bonded area, while other areas maintain a flexible design.

[0028] Operation process: 1. Material Lamination: Stack the cover layer, adhesive layer, copper foil, and substrate in sequence, and cure them through a thermo-pressing process. 2. Reinforcing Layer Processing: Apply high-modulus adhesive locally to the bonding area and attach the reinforcing cover layer. 3. Bonding Process: Perform thermo-pressing welding of the chip in the reinforcing area to ensure a smooth, wrinkle-free surface.

[0029] The FPC manufactured using the new design has the following beneficial effects: 1. Wrinkle elimination: The flatness of the bonding area is improved by 90%, and the wrinkle occurrence rate is reduced from 10% to below 0.5%. 2. Enhanced product reliability: The tensile strength of the reinforcing layer is increased by 50%, and the welding yield is improved to over 99%.

[0030] The above description is merely an illustration of preferred embodiments of the present invention, and the above technical features can be arbitrarily combined to form multiple embodiments of the present invention.

[0031] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the concept and technical solution of the present invention, or the direct application of the concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A layer structure for improving wrinkles in the bonding area of ​​an FPC, comprising a base laminate structure, wherein the extended portions of a substrate layer and an intermediate copper foil layer in the base laminate structure form the bonding area, characterized in that: A reinforcing layer structure is provided on one side of the extended substrate layer portion within the binding area, and the extended substrate layer portion is located between the extended intermediate copper foil layer portion and the reinforcing layer structure.

2. The layer structure for improving wrinkles in the FPC bonding region as described in claim 1, characterized in that: In the basic laminated structure, the upper side of the substrate layer is provided with an upper copper foil layer, an upper adhesive layer and an upper cover layer from the inside to the outside.

3. The layer structure for improving wrinkles in the FPC bonding region as described in claim 2, characterized in that: In the basic laminated structure, a lower adhesive layer and a lower cover layer are provided sequentially from the inside to the outside on the lower side of the middle copper foil layer.

4. The layer structure for improving wrinkles in the FPC bonding region as described in claim 1, characterized in that: The reinforcing layer structure includes a reinforcing adhesive layer and a reinforcing cover layer, wherein the reinforcing adhesive layer is located between the substrate layer and the reinforcing cover layer.

5. The layer structure for improving wrinkles in the FPC bonding region as described in claim 4, characterized in that: The thickness of the reinforcing adhesive layer ranges from 20 to 30 μm.

6. The layer structure for improving wrinkles in the FPC bonding region as described in claim 5, characterized in that: The thickness of the reinforcing cover layer ranges from 25 to 50 μm.

7. The layer structure for improving wrinkles in the FPC bonding region as described in claim 6, characterized in that: The reinforcing adhesive layer is a modified epoxy resin adhesive layer, and the reinforcing cover layer is a glass fiber reinforced polyimide layer.

8. The layer structure for improving wrinkles in the FPC bonding region as described in claim 7, characterized in that: The reinforcing cover layer contains copper foil sheets.

9. The layer structure for improving wrinkles in the FPC bonding region as described in claim 8, characterized in that: The copper foil sheet has a mesh structure.

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