Preparation process of thin-glue bending-resistant LED flexible circuit

Abstract

The invention discloses a preparation process of a thin-glue bending-resistant LED flexible circuit, and belongs to the field of LED flexible circuit board preparation, and the preparation process comprises the following steps: adopting a material with a glue layer thickness of 6-8 UM, and setting a double-sided material composition as copper, glue, PI, glue and copper; s2, performing line exposure and etching on the top copper foil in a roll-to-roll mode to form a circuit pattern; s3, through holes are formed through laser drilling, the thickness of an adhesive layer is detected through a sensor in the drilling process, the laser power or the scanning speed is adjusted by a control system according to detection data, and dynamic adjustment of the laser efficiency is achieved; the thickness of the adhesive layer is reduced to 6-8 UM, so that the flexibility of the copper foil is remarkably improved, the bending frequency of the circuit board is increased to 100 or more, and the high-flexibility application requirement is met; the glue layer thinning is combined with the laser efficiency dynamic adjustment technology, the glue shrinkage problem of laser drilling is reduced, and the drilling efficiency is improved; the electroplating process is simplified, the plasma cleaning step is omitted, meanwhile, material use is optimized, and the overall production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of LED flexible circuit board preparation, and particularly to a preparation process for a thin glue-resistant and bendable LED flexible circuit. Background Art

[0002] In the preparation of LED flexible circuit boards, the traditional double-sided material composition is usually copper + glue + PI + glue + copper, and the thickness of the glue is generally 20 - 40 UM. The glue plays an adhesive role, enabling good bonding between the double-sided copper foils and PI and preventing delamination and blistering. However, too thick glue will cause the board to become hard, seriously affecting the bending performance. Under the traditional process, the number of bends of the circuit board is usually within 3 times, making it difficult to meet scenarios with high flexibility requirements.

[0003] If a glue-free material is used, although the flexibility can be improved to a certain extent, the cost is relatively high and it is not suitable for LED products.

[0004] In the aspect of via hole processing technology, currently, mechanical punching or laser drilling is mainly used to produce infinitely long boards. Mechanical punching can only produce via hole diameters above 0.3 mm, and for via holes below 0.3 mm, laser drilling is required. However, mechanical drilling has the problem of glue pulling, and laser drilling has the problem of shrinkage. Moreover, when the glue layer is thick, the laser drilling efficiency is low, and it also affects the performance inside the holes during subsequent electroplating. For example, when laser drilling with a 20 UM glue thickness, the glue shrinkage is controlled within 15 ≦ mm, the laser efficiency is 11 times, and the conventional process requires steps such as laser drilling - plasma cleaning - black hole / electroplating - circuit, etc., with a cumbersome process and high cost;

[0005] Therefore, there is a lack of a preparation process for a thin glue-resistant and bendable LED flexible circuit to solve problems such as the influence of glue thickness on bending, low drilling efficiency, and high cost. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention provides a preparation process for a thin glue-resistant and bendable LED flexible circuit. By optimizing the glue layer thickness and processing technology, the bending performance and drilling efficiency of the circuit board are improved, and the production cost is reduced, solving problems such as the influence of glue thickness on bending, low drilling efficiency, and high cost.

[0007] Technical Solution: To solve the above technical problems, according to one aspect of the present invention, more specifically, a preparation process for a thin glue-resistant and bendable LED flexible circuit includes the following steps:

[0008] S1. Use a material with a glue layer thickness of 6 - 8 UM, and set the double-sided material composition to a structure of copper + glue + PI + glue + copper for combination;

[0009] S2. Form vias by laser drilling. During the drilling process, use a sensor to detect the thickness of the adhesive layer, and the control system adjusts the laser power or scanning speed according to the detected data to achieve dynamic adjustment of laser efficiency;

[0010] S3. Adopt roll-to-roll laser drilling;

[0011] S4. Plan reasonable parameters according to the aperture size, adhesive shrinkage, and copper thickness of the laser drilling, perform black hole and copper plating, and conduct the vias between the top copper foil and the bottom copper foil through electroless copper;

[0012] S5. Use the roll-to-roll method to expose and etch the top copper foil to form a circuit pattern;

[0013] S6. Paste a cover film on the upper end of the top copper foil to form a component pad layer;

[0014] S7. The customer solders components according to the pad layer to achieve the product function;

[0015] S8. Due to the thinner adhesive of the product, the flexibility of the product is achieved;

[0016] S9. The adhesive thickness between the top and bottom copper foils is thinned, the dielectric layer is reduced, the conduction current between the bottom and top copper foils is increased, and the heat dissipation is better. The light efficiency of the LED lamp is higher, and the loss of components is lower.

[0017] Furthermore, the dynamic adjustment of laser efficiency is specifically achieved through the following methods:

[0018] Sensor detection: Use a thickness sensor to monitor the thickness change of the adhesive in real time, and transmit the real-time measured data to the control system quickly and accurately through a high-speed data transmission interface; the thickness sensor can accurately measure the thickness of the adhesive layer at an extremely high frequency during the laser drilling process, and the measurement accuracy reaches the nanometer level;

[0019] Feedback control: The control system adjusts the laser power or scanning speed according to the sensor data to ensure that the laser energy matches the thickness of the adhesive; for example, when it is detected that the thickness of the adhesive layer increases, the control system increases the laser power proportionally to make the laser energy match the thickness of the adhesive layer, ensuring that the laser can smoothly penetrate the adhesive layer for drilling; when the thickness of the adhesive layer decreases, the control system correspondingly reduces the laser power to prevent over-drilling; at the same time, the control system will also dynamically adjust the scanning speed according to the real-time state of the laser drilling, such as the feedback information of drilling depth and drilling quality, to optimize the drilling efficiency and quality;

[0020] Algorithm Optimization: Through a preset algorithm or machine learning model, predict the optimal laser parameters to achieve dynamic adjustment. The preset algorithm is established based on a large amount of experimental data and theoretical analysis, and can calculate the optimal combination of laser power and scanning speed according to factors such as adhesive layer thickness, laser wavelength, and material properties. The machine learning model, on the other hand, learns and trains from a vast amount of drilling data to continuously optimize its prediction ability. As the production process continues, the machine learning model can automatically adapt to different production conditions and material changes, more accurately predict the optimal laser parameters, and further improve the efficiency and quality of laser drilling.

[0021] Closed-loop System: Establish a closed-loop control system to continuously monitor and adjust laser parameters. During the entire laser drilling process, the closed-loop control system continuously obtains the adhesive layer thickness data measured by sensors and the real-time state data of laser drilling, and compares these data with preset target values. According to the comparison results, the control system automatically adjusts the laser power and scanning speed, forming an ever-optimizing cycle process. Through this closed-loop control method, it is possible to timely compensate for changes in laser drilling parameters caused by material differences and equipment fluctuations, ensure the stability and consistency of drilling quality, and effectively reduce the occurrence of glue shrinkage problems.

[0022] Advantages of Adhesive Layer Thinning: After the adhesive layer is thinned, the energy required for laser drilling is reduced, and the phenomenon of glue shrinkage inside the glue is reduced. For laser drilling with a 20UM adhesive layer thickness, the glue shrinkage is controlled within 15≦mm, and the laser efficiency is 11 times. For laser drilling with a 6 - 8UM adhesive layer thickness, the glue shrinkage is controlled within 5≦mm, and the laser efficiency is increased to 7 times, improving the drilling efficiency and quality, significantly shortening the production cycle, and reducing problems such as via hole diameter deviation and rough hole walls caused by glue shrinkage.

[0023] Furthermore, when the adhesive layer thickness is 6 - 8UM, the number of times the circuit board can be bent can reach more than 100 times (by improving the adhesive layer thickness from the traditional 20 - 40UM to 6 - 8UM and using a glue with a specific ratio, the flexibility of the copper foil is significantly improved, and the number of times the circuit board can be bent is increased from within 3 times to more than 100 times).

[0024] Furthermore, during the processing of the via hole, for laser drilling with a 6 - 8UM adhesive layer thickness, the glue shrinkage is controlled within 5≦mm, and the laser efficiency is 7 times.

[0025] Furthermore, the electroplating process steps are laser drilling - black hole / electroplating - circuit, omitting the plasma cleaning step.

[0026] Furthermore, before forming the via hole, perform AOI inspection on the etched LED flexible circuit board.

[0027] Further, in the step S1, the PI material selected is polyimide with special surface treatment, and its surface roughness Ra is between 10 - 20 nm to enhance the adhesion force with the glue layer.

[0028] Further, in the step S2, the resolution of the exposure machine used during circuit exposure is not less than 50 μm, and the exposure energy is controlled within 100 - 150 mJ / cm² to ensure that the accuracy of the formed circuit pattern meets the requirements.

[0029] The beneficial effects of the preparation process of the thin - glue bend - resistant LED flexible circuit of the present invention are as follows:

[0030] (1) By reducing the glue layer thickness to 6 - 8 UM in the present invention, the flexibility of the copper foil is significantly improved, and the number of bending times of the circuit board is increased to more than 100 times, meeting the requirements of high - flexibility applications;

[0031] (2) The combination of reducing the glue layer thickness and the dynamic adjustment technology of laser efficiency reduces the problem of glue shrinkage during laser drilling, improves the drilling efficiency, and the 6 - 8 UM glue thickness improves the laser efficiency;

[0032] (3) Simplify the electroplating process, eliminate the plasma cleaning step, and at the same time optimize the material use, reducing the overall production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The following further describes the present invention in detail with reference to the drawings and specific implementation methods.

[0034] Figure 1 is the flow chart of the present invention;

[0035] Figure 2 is the process schematic diagram of the present invention;

[0036] Figure 3 is the schematic diagram of the traditional process. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The present invention will be described in detail below with reference to the drawings and embodiments. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0038] To make the technical solution of the present invention clearer, the following further describes the present invention in detail with reference to the drawings and specific embodiments.

[0039] Refer to Figures 1-3 , a preparation process of a thin - glue bend - resistant LED flexible circuit, and the specific implementation steps are as follows:

[0040] For circuit exposure and etching, the top - layer copper foil is subjected to circuit exposure in a roll - to - roll manner, and the exposed top - layer copper foil is etched to form a circuit pattern.

[0041] AOI inspection: Conduct AOI inspection on the etched LED flexible circuit board to ensure that the circuit pattern meets the requirements.

[0042] Laser drilling: In the positions where the top copper foil has been pre-etched off, by identifying several MAKE points of the circuit, use the laser to pass through the top copper foil and the PI adhesive layer to form blind vias.

[0043] During the laser drilling process, the adhesive layer thickness is monitored in real time through a sensor, and the control system dynamically adjusts the laser power and scanning speed according to the monitored data to ensure the drilling quality and efficiency.

[0044] SMT component mounting and reflow soldering: Apply solder paste by SMT component mounting at the positions of several blind vias, and make the top copper foil and the bottom copper foil conduct through molten tin by reflow soldering. Paste the cover film: Paste the cover film on the upper end of the top copper foil to protect the LED flexible circuit board.

[0045] Circular operation: Use the roll-to-roll method to repeat the above steps for the next operation position of the infinitely long flexible circuit board to complete the preparation of the entire circuit board.

[0046] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation process of a thin glue bend-resistant LED flexible circuit, characterized in that, It includes the following steps: S1. Adopt a material with an adhesive layer thickness of 6 - 8 UM, and set the double-sided material to a structure of copper + adhesive + PI + adhesive + copper for combination; S2. Form vias through laser drilling. During the drilling process, use a sensor to detect the adhesive layer thickness, and the control system adjusts the laser power or scanning speed according to the detected data to achieve dynamic adjustment of laser efficiency; S3. Adopt roll-to-roll laser drilling; S4. Plan reasonable parameters according to the aperture size, adhesive shrinkage, and copper thickness of the laser drilling, perform black hole and electroplated copper, and conduct the vias between the top copper foil and the bottom copper foil through chemical copper; S5. Use the roll-to-roll method to expose and etch the circuit pattern on the top copper foil; S6. Paste a cover film on the upper end of the top copper foil to form a component pad layer; S7. The customer solders components according to the pad layer to achieve the product function; S8. Due to the thinning of the product adhesive, the flexibility of the product is achieved; S9. The adhesive thickness between the top and bottom copper foils is thinned, the dielectric layer is reduced, the conduction current between the bottom and top copper foils is increased, and the heat dissipation is better. The light efficiency of the LED lamp is higher, and the loss of components is lower.

2. The preparation process of a thin glue bend-resistant LED flexible circuit according to claim 1, characterized in that: The dynamic adjustment of the laser efficiency is specifically achieved through the following methods: Sensor detection: Use a thickness sensor to monitor the thickness change of the adhesive in real time, and transmit the real-time measured data to the control system quickly and accurately through a high-speed data transmission interface; the thickness sensor can accurately measure the adhesive layer thickness at a very high frequency during the laser drilling process, and the measurement accuracy reaches the nanometer level; Feedback control: The control system adjusts the laser power or scanning speed according to the sensor data to ensure that the laser energy matches the adhesive thickness; for example, when it is detected that the adhesive layer thickness increases, the control system increases the laser power proportionally to make the laser energy match the adhesive layer thickness, ensuring that the laser can penetrate the adhesive layer smoothly for drilling; when the adhesive layer thickness decreases, the control system reduces the laser power accordingly to prevent over-drilling; at the same time, the control system will also dynamically adjust the scanning speed according to the real-time state of the laser drilling, such as the drilling depth and drilling quality feedback information, to optimize the drilling efficiency and quality; Algorithm optimization: Predict the best laser parameters through a preset algorithm or a machine learning model to achieve dynamic adjustment; the preset algorithm is established based on a large amount of experimental data and theoretical analysis, and can calculate the best combination of laser power and scanning speed according to factors such as the adhesive layer thickness, laser wavelength, and material properties; while the machine learning model learns and trains from a large amount of drilling data to continuously optimize its prediction ability; as the production process continues, the machine learning model can automatically adapt to different production conditions and material changes, and more accurately predict the best laser parameters to further improve the efficiency and quality of laser drilling; Closed-loop system: Establish a closed-loop control system to continuously monitor and adjust the laser parameters; during the entire laser drilling process, the closed-loop control system continuously obtains the data of the adhesive layer thickness measured by the sensor and the real-time state data of the laser drilling, and compares these data with the preset target values; according to the comparison results, the control system automatically adjusts the laser power and scanning speed to form a continuously optimized cycle process; through this closed-loop control method, it is possible to timely compensate for the changes in the laser drilling parameters caused by material differences and equipment fluctuations, ensure the stability and consistency of the drilling quality, and effectively reduce the occurrence of adhesive shrinkage problems; Advantages of adhesive layer thinning: After the adhesive layer is thinned, the energy required for laser drilling is reduced, and the adhesive shrinkage phenomenon is reduced; for laser drilling with a 20UM adhesive thickness, the adhesive shrinkage is controlled within 15≦mm, and the laser efficiency is 11 times; for laser drilling with a 6-8UM adhesive thickness, the adhesive shrinkage is controlled within 5≦mm, and the laser efficiency is increased to 7 times, improving the drilling efficiency and quality, greatly shortening the production cycle, and reducing the problems of via hole diameter deviation and rough hole wall caused by adhesive shrinkage.

3. The preparation process of a thin glue bend-resistant LED flexible circuit according to claim 1, characterized in that: The thickness of the adhesive layer is 6-8UM, and the number of times the circuit board can be bent can reach more than 100 times.

4. The preparation process of a thin glue bend-resistant LED flexible circuit according to claim 1, characterized in that: During the processing of the via hole, the adhesive shrinkage of laser drilling with a 6-8UM adhesive thickness is controlled within 5≦mm, and the laser efficiency is 7 times.

5. The preparation process of a thin glue bend-resistant LED flexible circuit according to claim 1, characterized in that: The electroplating process steps are laser drilling - black hole / electroplating - circuit, omitting the plasma cleaning step.

6. The preparation process of a thin glue bend-resistant LED flexible circuit according to claim 1, characterized in that: Before forming the via hole, perform AOI inspection on the etched LED flexible circuit board.

7. The preparation process of a thin glue bend-resistant LED flexible circuit according to claim 1, characterized in that: In the S1 step, the selected PI material is polyimide with special surface treatment, and its surface roughness Ra is between 10-20nm to enhance the adhesion to the adhesive layer.

8. The preparation process of a thin glue bend-resistant LED flexible circuit according to claim 1, characterized in that: In the S2 step, the resolution of the exposure machine used during circuit exposure is not less than 50μm, and the exposure energy is controlled within 100-150mJ / cm² to ensure that the accuracy of the formed circuit pattern meets the requirements.

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