Laser transmission welding method and device for flexible circuit packaging

Abstract

The invention relates to the technical field of laser transmission welding, in particular to a laser transmission welding method and device for flexible circuit packaging, and the method comprises the steps that a plurality of mounting holes are formed in a substrate, absorption pieces with the same number as the mounting holes are attached to a to-be-welded element, and each absorption piece comprises a light absorption layer and a heat conduction layer; the absorption piece is aligned with the mounting hole, laser is used for sequentially irradiating the light absorption layer, so that the light absorption layer absorbs laser energy and then generates heat, and local welding of the element to be welded and the substrate is achieved under the cooperation of the light absorption layer and the mounting hole; wherein in the welding process, the temperature of a welding area is monitored, whether the temperature of the element to be welded and the temperature of the substrate in the welding process are smaller than a set temperature threshold value or not is judged, and if the temperature is larger than or equal to the temperature threshold value, the laser power is automatically adjusted. Accurate control over the welding temperature and stability of the welding quality can be guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of laser transmission welding, and in particular to a laser transmission welding method and device for flexible circuit packaging. Background Art

[0002] Flexible circuits have been widely used in electronic skin, wearable devices, flexible displays and other fields due to their thinness, softness and bendability. The manufacture of flexible electronic devices requires the close integration of micro sensors, high-density circuits and flexible substrates to achieve complex functions. The sensitivity of these sensors to temperature, mechanical pressure and changes in the external environment determines that they have special requirements in the packaging process. However, the packaging process of flexible circuits is a key link that affects their performance and reliability. It is necessary not only to ensure the stable connection between the sensor and the substrate, but also to meet the durability requirements for long-term use. Traditional packaging technology mainly relies on gluing and hot pressing processes, but these methods have exposed many problems in practical applications, especially in preventing thermal damage, and it is difficult to meet the high-precision, high-reliability and high-efficiency production requirements of modern flexible electronic devices.

[0003] In addition, as flexible electronic devices become increasingly miniaturized and complex, the requirements for packaging technology are becoming increasingly stringent, including higher positioning accuracy, stronger mechanical strength, and shorter processing time, while traditional processes have obvious shortcomings in these aspects. Therefore, developing a high-precision and high-efficiency packaging process, especially a fast fixing technology for micro sensors, has become an urgent problem to be solved.

[0004] The disadvantages of traditional technology are as follows: 1. Thermosensitive materials are susceptible to damage: High temperature and hot pressing can easily cause thermal damage or deformation of thin film flexible substrates and micro sensors, seriously affecting the performance and long-term stability of the sensors.

[0005] 2. Insufficient packaging precision: The gluing process is prone to poor alignment or insufficient bonding strength, which affects the packaging effect.

[0006] 3. Low production efficiency: The traditional process steps are complicated, time-consuming, and difficult to meet large-scale production needs.

[0007] Laser transmission welding is a high-precision, non-contact processing method that can achieve fast and efficient welding by utilizing the difference in optical transmittance and absorption of materials, which is suitable for flexible electronic packaging needs. However, the existing technology has not yet provided an optimized laser transmission welding method for fixing and sealing micro sensors in flexible circuits. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a laser transmission welding method and device for flexible circuit packaging, which realizes precise heating of the welding area and avoids excessive heat on the sensitive elements of the sensor. At the same time, combined with the optical monitoring and feedback system, the laser power and irradiation time are dynamically adjusted to ensure that the temperature during the welding process is always kept within a safe range, further preventing high temperature from damaging sensitive components. The laser transmission welding method includes the following steps: S1: a plurality of mounting holes are arranged on the substrate, and an absorption sheet having the same number as the mounting holes is attached to the component to be welded, wherein the absorption sheet comprises a light absorbing layer and a heat conducting layer; S2: aligning the absorption sheet with the mounting hole, using laser to sequentially irradiate the light absorbing layer, so that the light absorbing layer generates heat after absorbing laser energy, and realizing partial welding of the component to be welded and the substrate under the cooperation of the light absorbing layer and the mounting hole; During the welding process, the temperature of the welding area is monitored, and it is determined whether the temperature of the element to be welded and the substrate is less than a set temperature threshold. If the temperature is greater than or equal to the temperature threshold, the laser power is automatically adjusted.

[0009] In one embodiment of the present invention, in S2, the method of aligning the absorption sheet with the mounting hole comprises: S21: collecting a welding area image and extracting its multimodal features, wherein the multimodal features include edge features, corner features and texture features; S22: monitoring the temperature distribution data and deformation data of the welding area in real time, and inputting the temperature distribution data and the deformation data into a deformation model constructed in advance to obtain a predicted deformation amount; S23: dynamically adjusting the weights of different types of features in the multimodal features according to the predicted deformation amount to obtain optimized feature points; S24: aligning the optimized feature points, removing mismatched points, and obtaining a preprocessed set of matching point pairs; S25: Based on the set of matching point pairs, a geometric mapping relationship between the image of the component to be welded and the image of the substrate is calculated to obtain a transformation matrix; S26: adjusting the position of the absorbing disc of the component to be welded to be aligned with the position of the mounting hole of the substrate in real time according to the transformation matrix.

[0010] In one embodiment of the present invention, in S24, the method for obtaining the preprocessed matching point pair set includes: Based on the feature points after the coordinate adjustment, the feature points are divided into multiple sub-areas, the number of feature points in each sub-area is counted, and the distribution density in each sub-area is calculated; Preliminary matching is performed on the feature points after the coordinate adjustment to obtain a set of matching point pairs, and for each matching point pair, a matching score of each matching point pair is calculated based on the descriptor similarity of the feature points; at the same time, geometric transformation fitting is performed on each matching point pair to calculate the fitting error; Calculating a matching confidence according to the matching score and the fitting error, dynamically adjusting a threshold of the RANSAC algorithm according to the distribution density and the matching confidence, eliminating mismatching points through the adjusted threshold, and obtaining a preprocessed matching point pair set; Each matching point pair includes a feature point in the image of the component to be welded and a feature point in the image of the substrate.

[0011] In one embodiment of the present invention, in S25, the method for obtaining the transformation matrix is ​​as follows: For feature points whose local deformation amount is less than the deformation threshold, an affine transformation matrix is ​​used to adjust the position of the absorption disc to align with the mounting hole; For feature points whose local deformation amount is greater than or equal to the deformation threshold, the transmission transformation matrix is ​​used to adjust the position of the absorption disk to align with the mounting hole.

[0012] In one embodiment of the present invention, the method for obtaining the affine transformation matrix is ​​as follows: Define the number of matching point pairs in the matching point pair set as n, and record the matching point pairs as ,in is the coordinate of the feature point in the image of the component to be welded, For the coordinates of the feature points in the base image, construct matrices P and Q, where matrix P contains all , the matrix Q contains all : , Use the following formula to solve the affine transformation matrix A: .

[0013] In one embodiment of the present invention, the method for obtaining the transmission transformation matrix is ​​as follows: Define the number of matching point pairs in the matching point pair set as n, and record the matching point pairs as ,in is the coordinate of the feature point in the image of the component to be welded, For the coordinates of the feature points in the base image, construct matrices P and Q, where matrix P contains all , the matrix Q contains all : , The transmission transformation matrix H is solved using the following formula: .

[0014] In one embodiment of the present invention, in S22, the method for constructing the deformation model is: Obtain temperature change data of welding area and local shape variables ,according to and , establish a thermal-mechanical coupling deformation prediction model: ,in, , , are thermal expansion coefficient, stress sensitivity factor and transient deformation coefficient, respectively. is external stress.

[0015] In one embodiment of the present invention, in S23, the formula for dynamically adjusting the weights of different features in the multimodal features is as follows: ,in, For the i The weight of the feature, For the i The deformation of the characteristic area, is the adjustment factor.

[0016] In one embodiment of the present invention, in S23, the method of dynamically adjusting the weights of different types of features in the multimodal features according to the predicted deformation amount also includes: for areas where the degree of deformation exceeds a preset deformation threshold, increasing the weight of texture features; for areas where the degree of deformation does not exceed the preset deformation threshold, increasing the weights of edge features and corner features.

[0017] Based on the same inventive concept, the present invention also provides a laser transmission welding device for flexible circuit packaging, the device comprising: A base, wherein the base is provided with a plurality of mounting holes; An absorption sheet having the same number as the mounting holes, the absorption sheet comprising a light absorbing layer and a heat conducting layer, the heat conducting layer being attached to the component to be welded, and the size of the absorption sheet being smaller than the mounting holes; And a control unit, the control unit executes the steps of the laser transmission welding method for flexible circuit packaging, aligns the absorption sheet with the mounting hole, uses laser to irradiate the light absorbing layer in sequence, so that the light absorbing layer generates heat after absorbing laser energy, and realizes partial welding of the component to be welded and the substrate under the cooperation of the light absorbing layer and the mounting hole.

[0018] In one embodiment of the present invention, the laser transmission welding device further includes an infrared thermal imager and a laser displacement sensor, wherein the infrared thermal imager and the laser displacement sensor are respectively installed at designated positions close to the welding area and are both connected to the control unit.

[0019] In one embodiment of the present invention, the laser transmission welding device further comprises a camera device, and the laser displacement sensor of the camera device is installed at a designated position close to the welding area and is connected to the control unit.

[0020] The present invention also provides a computer storage medium, wherein the computer storage medium stores a computer software product, wherein the computer software product includes several instructions for enabling a computer device to execute the laser transmission welding method for flexible circuit packaging.

[0021] The above technical solution of the present invention has the following advantages compared with the prior art: The present invention uses local laser heating technology, combined with light-absorbing media and thermally conductive materials, to achieve precise heating of the welding area. The light-absorbing medium efficiently absorbs laser energy and converts it into heat, while the thermally conductive material evenly disperses the heat, avoiding excessive heat effects on the sensor's sensitive elements. At the same time, the present invention integrates an optical monitoring and feedback system to monitor the temperature changes in the welding area in real time, and dynamically adjusts the laser power and irradiation time through a PID control algorithm to ensure that the temperature during the welding process is always kept within a safe range, further preventing damage to sensitive components caused by high temperatures. This process ensures precise control of the welding temperature and stability of the welding quality through a real-time feedback mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 It is a schematic flow chart of a laser transmission welding method for flexible circuit packaging provided in an embodiment of the present invention; Figure 2 is a schematic flow chart of a method for aligning the absorbent sheet with the mounting hole provided in an embodiment of the present invention; Figure 3 It is a partial structural schematic diagram of a laser transmission welding device for flexible circuit packaging provided in an embodiment of the present invention; Figure 4 It is a partial structural schematic diagram of a laser transmission welding device for flexible circuit packaging provided in an embodiment of the present invention; Explanation of the reference numerals in the specification: 1. Base; 11. Mounting hole; 2. Absorbent sheet; 3. Welding gun; 4. Control unit; 5. Infrared thermal imager; 6. Laser displacement sensor; 7. Camera device; 8. Component to be welded. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0024] Embodiment 1:

[0025] like Figure 1 As shown, the present invention provides a laser transmission welding method comprising the following steps: S1: a plurality of mounting holes are arranged on a substrate made of a transparent flexible polymer (such as PET or PDMS), and an absorption sheet having the same number as the mounting holes is attached to a component to be welded (such as a micro sensor), wherein the absorption sheet comprises a light absorbing layer and a heat conducting layer; S2: aligning the absorption sheet with the mounting hole, using laser to sequentially irradiate the light absorption layer in the form of multi-point or line welding, so that the light absorption layer generates heat after absorbing laser energy, and realizing partial welding of the component to be welded and the substrate under the cooperation of the light absorption layer and the mounting hole; During the welding process, the temperature of the welding area is monitored, and it is determined whether the temperature of the element to be welded and the substrate is less than a set temperature threshold. If the temperature is greater than or equal to the temperature threshold, the laser power is automatically adjusted.

[0026] Specifically, during the welding process, the welding parameters are controlled in real time through the optical monitoring and feedback system to prevent the sensor sensitive components from being damaged by high temperature. The infrared thermal imaging system continuously monitors the temperature dynamics of the welding area to ensure that the temperature is maintained within the preset safety threshold. Specifically, the infrared thermal imaging camera captures the thermal map of the welding area, where each pixel corresponds to the temperature value at that location. The system analyzes these temperature data in real time, and once a hot spot area is detected where the temperature exceeds the safety threshold, the automatic adjustment mechanism of the laser power is immediately triggered. Based on the real-time thermal map data, the laser control system uses the PID control strategy to dynamically adjust the laser power by adjusting the proportional (P), integral (I) and differential (D) parameters to adapt to temperature deviations: Proportional (P) control: adjusts the laser power according to the deviation between the current temperature and the target temperature. The greater the deviation, the greater the power adjustment.

[0027] Integral (I) control: accumulates small temperature deviations over a long period of time to prevent the temperature from continuously deviating from the target value.

[0028] Differential (D) control: predicts temperature change trends and adjusts laser power in advance to avoid excessive temperature fluctuations.

[0029] With the help of PID control, the system can accurately control the laser power and effectively prevent high temperature from damaging the sensitive components of the sensor. In view of the low thermal conductivity and high thermal expansion coefficient of flexible materials, the PID control algorithm has been deeply optimized. Specific optimization measures include: Dynamic proportional parameter adjustment mechanism: adjust the proportional gain in real time according to the temperature change rate. When the temperature change rate is high, increase the proportional gain to achieve a fast response; when the temperature is close to the target value, reduce the proportional gain to avoid overshoot.

[0030] Integral limiting mechanism: Based on the thermal expansion characteristics of flexible materials, the size of the integral term is limited to prevent temperature fluctuations caused by excessive integral terms.

[0031] Differential item prediction function: Combined with the differential item prediction function, infrared thermal imaging data is used to compensate for hot spots in advance to avoid damage to sensitive components due to excessive temperature gradients.

[0032] The dynamic adjustment mechanism ensures that sensitive components will not be damaged by overheating. The entire welding process ensures that the temperature distribution is always within a safe range through continuous feedback and correction.

[0033] The visual feedback system collects images of the welding area through a high-resolution camera, extracts multimodal features (edges, corners, textures), and dynamically adjusts the feature weights according to the transparency and deformation characteristics of the welding area; uses infrared thermal imagers and laser displacement sensors to monitor deformation in real time, and adjusts the registration results through a deformation compensation mechanism; the optimized RANSAC algorithm dynamically adjusts the threshold according to the distribution density of feature points and matching confidence, removes mismatched points, and improves matching accuracy; finally, by calculating the transformation matrix, the alignment of the sensor and the substrate is adjusted in real time to ensure the accuracy of the welding point. The entire process optimizes welding accuracy through real-time image analysis and feedback mechanisms to ensure high quality and high reliability of packaging.

[0034] See also Figure 2 As shown, in S2, based on the visual feedback system, the method for aligning the absorption sheet with the mounting hole includes: S21: collecting welding area images by using a high-resolution industrial camera, and extracting multimodal features thereof by using image processing technology, wherein the multimodal features include edge features, corner features, and texture features; S22: monitoring the temperature distribution data and deformation data of the welding area in real time, and inputting the temperature distribution data and the deformation data into a deformation model constructed in advance to obtain a predicted deformation amount; S23: According to the predicted deformation amount, dynamically adjust the weights of different types of features in the multimodal features to obtain optimized feature points; specifically, for areas with a larger deformation degree, texture features are used preferentially because texture features are insensitive to deformation; for areas with a smaller deformation degree, edge and corner features are used preferentially because these features are more sensitive to local details. The formula for dynamically adjusting the weights of different types of features in the multimodal features is as follows: ,in, For the i The weight of the feature, For the i The deformation of the characteristic area, To adjust the coefficient; by dynamically adjusting the feature weights, the system can adapt to the deformation characteristics of the welding area to ensure the registration accuracy; S24: aligning the optimized feature points, removing mismatched points, and obtaining a preprocessed set of matching point pairs; S25: Based on the set of matching point pairs, a geometric mapping relationship between the image of the component to be welded and the image of the substrate is calculated to obtain a transformation matrix; S26: adjusting the position of the absorbing disc of the component to be welded to be aligned with the position of the mounting hole of the substrate in real time according to the transformation matrix.

[0035] Optionally, in S22, the deformation model is constructed based on the physical model as follows: Obtain temperature change data of welding area and local shape variables ,according to and , establish a thermal-mechanical coupling deformation prediction model: ,in, , , are thermal expansion coefficient, stress sensitivity factor and transient deformation coefficient, respectively. is external stress.

[0036] Optionally, the deformation model can also be based on a deep learning model, using a deep learning algorithm (such as a convolutional neural network CNN) to learn deformation laws from a large amount of temperature distribution and deformation data. After the model training is completed, new temperature distribution data can be input to predict the corresponding deformation amount. The training data used includes temperature distribution data, material property data, and actual deformation data. The mean square error (MSE) or mean absolute error (MAE) is used to measure the difference between the predicted value and the true value.

[0037] In addition, we can also combine the physical model and the deep learning model to build a deformation model, first make a preliminary prediction through the physical model, and then make corrections through the deep learning model. This method can improve the accuracy and generalization ability of the model.

[0038] In S23 of this embodiment, the method of dynamically adjusting the weights of different types of features in the multimodal features according to the predicted deformation amount also includes: for areas where the degree of deformation exceeds a preset deformation threshold, increasing the weight of texture features; for areas where the degree of deformation does not exceed the preset deformation threshold, increasing the weights of edge features and corner features.

[0039] The traditional RANSAC algorithm uses a fixed threshold to remove false matching points, but in flexible scenes, due to material deformation and transparency, the fixed threshold may cause valid matching points to be mistakenly removed. To this end, the present invention introduces an adaptive threshold adjustment mechanism to dynamically adjust the threshold according to the distribution density of feature points and matching confidence. Further, in S24, the method for obtaining the preprocessed matching point pair set includes: Based on the feature points after the coordinate adjustment, the feature points are divided into a plurality of sub-areas, the number of feature points in each sub-area is counted, and the distribution density in each sub-area is calculated; The feature points after the coordinate adjustment are preliminarily matched using the RANSAC algorithm to obtain a set of matching point pairs, and for each matching point pair, a matching score of each matching point pair is calculated based on the descriptor similarity of the feature points; at the same time, a geometric transformation fitting is performed on each matching point pair to calculate the fitting error; Calculating a matching confidence according to the matching score and the fitting error, dynamically adjusting a threshold of the RANSAC algorithm according to the distribution density and the matching confidence, eliminating mismatching points through the adjusted threshold, and obtaining a preprocessed matching point pair set; Each matching point pair includes a feature point in the image of the component to be welded and a feature point in the image of the substrate.

[0040] When the threshold is adjusted, the RANSAC algorithm will re-evaluate all matching point pairs and determine which matching point pairs are valid and which are mismatched based on the new threshold. Matching point pairs that were previously eliminated but meet the new threshold conditions will be retained; matching point pairs that were previously retained but do not meet the new threshold conditions will be eliminated again. At the same time, the system will recalculate the matching scores of the matching point pairs and screen them in combination with geometric consistency verification. Matching point pairs with higher matching scores will be retained first, while matching point pairs with lower scores may be eliminated. By dynamically adjusting the threshold, the system can optimize the matching results in real time based on the distribution density and confidence of the current matching point pairs.

[0041] For example, in areas with high feature point density, the threshold is lowered to more strictly remove false matching points; in areas with low feature point density, the threshold is increased to avoid falsely removing valid matching points. This dynamic adjustment mechanism can significantly improve matching accuracy, especially in flexible materials or complex scenes, and effectively reduce the impact of false matching on the final result.

[0042] Furthermore, in S25, the method of obtaining the transformation matrix is ​​as follows: For feature points whose local deformation amount is less than the deformation threshold, an affine transformation matrix is ​​used to adjust the position of the absorption disc to align with the mounting hole; For feature points whose local deformation amount is greater than or equal to the deformation threshold, the transmission transformation matrix is ​​used to adjust the position of the absorption disk to align with the mounting hole.

[0043] Furthermore, the method for obtaining the affine transformation matrix is ​​as follows: Define the number of matching point pairs in the matching point pair set as n, and record the matching point pairs as ,in is the coordinate of the feature point in the image of the component to be welded, For the coordinates of the feature points in the base image, construct matrices P and Q, where matrix P contains all , the matrix Q contains all : , Use the following formula to solve the affine transformation matrix A: .

[0044] Furthermore, the method for obtaining the transmission transformation matrix is ​​as follows: Define the number of matching point pairs in the matching point pair set as n, and record the matching point pairs as ,in is the coordinate of the feature point in the image of the component to be welded, For the coordinates of the feature points in the base image, construct matrices P and Q, where matrix P contains all , the matrix Q contains all : , The transmission transformation matrix H is solved using the following formula: .

[0045] If there is a misalignment between the absorber and the mounting hole, the system will automatically adjust the laser focus position or the laser irradiation area to ensure the accuracy of the welding point. In addition, the system will monitor the shape changes during the welding process to ensure that the welding points are uniform and meet the predetermined standards. If an abnormality is found, the vision system will promptly feedback and adjust the welding parameters, such as laser power or focus size, to optimize the welding quality. This process continuously optimizes the welding accuracy through real-time image analysis and feedback mechanism to ensure the high quality and reliability of the final package.

[0046] Embodiment 2: like Figure 3 and Figure 4 As shown, based on the same inventive concept as that of the first embodiment, the present invention further provides a laser transmission welding device for flexible circuit packaging, the device comprising: a substrate 1 , an absorbing sheet 2 , a welding gun 3 and a control unit 4 .

[0047] The base 1 is provided with a plurality of mounting holes 11 with a diameter of 0.1 mm to 0.3 mm, so as to reduce the risk of thermal stress concentration during welding, thereby avoiding deformation of the film due to thermal stress and ensuring the flatness of the film; The number of the absorption sheets 2 is the same as the number of the mounting holes 11, and the absorption sheets 2 include a light absorbing layer and a heat conducting layer. The heat conducting layer is attached to the component to be welded 8, and the size of the absorption sheets 2 is smaller than the mounting holes 11; The control unit 4 controls the connection of the welding gun 3, and synchronously executes the steps of the laser transmission welding method for flexible circuit packaging described in the first embodiment, aligns the absorption sheet 2 with the mounting hole 11, and uses laser to irradiate the light absorbing layer in sequence, so that the light absorbing layer generates heat after absorbing laser energy, and realizes partial welding of the component to be welded 8 and the substrate 1 under the cooperation of the light absorbing layer and the mounting hole 11.

[0048] Preferably, the substrate 1 is made of a transparent flexible polymer (such as PET or PDMS) with high light transmittance and a thickness of 50 μm-200 μm.

[0049] The shape of the absorbent sheet 2 includes but is not limited to a circle, and can also be designed as a line, a square or other geometric shapes. Preferably, in this embodiment, the absorbent sheet 2 is a micro double-layer absorbent disc with a diameter of 0.5 mm to 1 mm and a thickness of 10 μm to 50 μm.

[0050] Preferably, the light absorbing layer includes, but is not limited to, carbon black, Clearweld material, graphene, and nanoparticle coating, which effectively absorbs laser light and converts energy into heat. The heat conducting layer is a thermally conductive material such as graphite, copper, aluminum, or silicon nitride. During the welding process, the heat conducting layer disperses heat to a larger area to prevent damage to sensitive components caused by local overheating.

[0051] Furthermore, the laser transmission welding device also includes an infrared thermal imager 5 and a laser displacement sensor 6 , which are respectively installed at designated positions close to the welding area and are both connected to the control unit 4 .

[0052] Furthermore, the laser transmission welding device also includes a camera device 7 , which is installed at a designated position close to the welding area and connected to the control unit 4 .

[0053] Preferably, the camera device 7 is a high-resolution industrial camera. The laser welding parameters of the welding gun 3 are set according to the material properties, the laser wavelength of 808nm, 980nm or 1064nm is selected, the laser power is adjusted to 2W~5W, the focus diameter is adjusted to 0.2mm~0.5mm, and the single-point irradiation time is set to 50ms~200ms, so as to ensure that both welding can be achieved and overheating damage can be avoided during the welding process.

[0054] When the welding operation starts, the control unit 4 focuses the laser on the four corners of the component 8 to be welded and the mounting hole 1 area of ​​the substrate 1, and irradiates point by point according to preset parameters. After the light-absorbing layer of the absorber 2 absorbs the laser energy, it heats up rapidly, generating local high temperature, melting the substrate material and forming a firm welding point with the sensor. At the same time, the thermal conductive layer disperses excess heat to prevent thermal damage to sensitive components. After all welding points are completed, the laser irradiation is stopped and the components are naturally cooled to room temperature to prevent deformation or detachment of the joints due to human intervention. After welding is completed, the components must undergo quality inspection, use tensile testing equipment to evaluate whether the strength of the welding points meets the design requirements, and use sealing tests to check whether the package has problems such as air leakage and liquid leakage to ensure that the welding quality meets the actual application requirements.

[0055] Embodiment three: The present invention also provides a computer storage medium, which stores a computer software product. The computer software product includes several instructions for enabling a computer device to execute the laser transmission welding method for flexible circuit packaging described in Example 1.

[0056] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0057] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0058] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0059] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0060] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A laser transmission welding method for flexible circuit packaging, characterized in that: The laser transmission welding method comprises the following steps: S1: a plurality of mounting holes are arranged on the substrate, and an absorption sheet having the same number as the mounting holes is attached to the component to be welded, wherein the absorption sheet comprises a light absorbing layer and a heat conducting layer; S2: aligning the absorption sheet with the mounting hole, using laser to sequentially irradiate the light absorbing layer, so that the light absorbing layer generates heat after absorbing laser energy, and realizing partial welding of the component to be welded and the substrate under the cooperation of the light absorbing layer and the mounting hole; During the welding process, the temperature of the welding area is monitored, and it is determined whether the temperature of the element to be welded and the substrate is less than a set temperature threshold. If the temperature is greater than or equal to the temperature threshold, the laser power is automatically adjusted.

2. The laser transmission welding method for flexible circuit packaging according to claim 1, characterized in that: In S2, the method of aligning the absorption sheet with the mounting hole includes: S21: collecting a welding area image and extracting its multimodal features, wherein the multimodal features include edge features, corner features and texture features; S22: monitoring the temperature distribution data and deformation data of the welding area in real time, and inputting the temperature distribution data and the deformation data into a deformation model constructed in advance to obtain a predicted deformation amount; S23: dynamically adjusting the weights of different types of features in the multimodal features according to the predicted deformation amount to obtain optimized feature points; S24: aligning the optimized feature points, removing mismatched points, and obtaining a preprocessed set of matching point pairs; S25: Based on the set of matching point pairs, a geometric mapping relationship between the image of the component to be welded and the image of the substrate is calculated to obtain a transformation matrix; S26: adjusting the position of the absorbing disc of the component to be welded to be aligned with the position of the mounting hole of the substrate in real time according to the transformation matrix.

3. The laser transmission welding method for flexible circuit packaging according to claim 2, characterized in that: In S24, the method for obtaining the preprocessed matching point pair set includes: Based on the feature points after the coordinate adjustment, the feature points are divided into multiple sub-areas, the number of feature points in each sub-area is counted, and the distribution density in each sub-area is calculated; Preliminary matching is performed on the feature points after the coordinate adjustment to obtain a set of matching point pairs, and for each matching point pair, a matching score of each matching point pair is calculated based on the descriptor similarity of the feature points; at the same time, geometric transformation fitting is performed on each matching point pair to calculate the fitting error; Calculating a matching confidence according to the matching score and the fitting error, dynamically adjusting a threshold of the RANSAC algorithm according to the distribution density and the matching confidence, eliminating mismatching points through the adjusted threshold, and obtaining a preprocessed matching point pair set; Each matching point pair includes a feature point in the image of the component to be welded and a feature point in the image of the substrate.

4. The laser transmission welding method for flexible circuit packaging according to claim 2, characterized in that: In S25, the method of obtaining the transformation matrix is ​​as follows: For feature points whose local deformation amount is less than the deformation threshold, an affine transformation matrix is ​​used to adjust the position of the absorption disc to align with the mounting hole; For feature points whose local deformation amount is greater than or equal to the deformation threshold, the transmission transformation matrix is ​​used to adjust the position of the absorption disk to align with the mounting hole.

5. The laser transmission welding method for flexible circuit packaging according to claim 4, characterized in that: The method for obtaining the affine transformation matrix is ​​as follows: Define the number of matching point pairs in the matching point pair set as n, and record the matching point pairs as ,in is the coordinate of the feature point in the image of the component to be welded, For the coordinates of the feature points in the base image, construct matrices P and Q, where matrix P contains all , the matrix Q contains all : ， Use the following formula to solve the affine transformation matrix A: .

6. The laser transmission welding method for flexible circuit packaging according to claim 4, characterized in that: The method for obtaining the transmission transformation matrix is ​​as follows: Define the number of matching point pairs in the matching point pair set as n, and record the matching point pairs as ,in is the coordinate of the feature point in the image of the component to be welded, For the coordinates of the feature points in the base image, construct matrices P and Q, where matrix P contains all , the matrix Q contains all : ， The transmission transformation matrix H is solved using the following formula: .

7. The laser transmission welding method for flexible circuit packaging according to claim 2, characterized in that: In S22, the deformation model is constructed by: Obtain temperature change data of welding area and local shape variables ,according to and , establish a thermal-mechanical coupling deformation prediction model: ,in, , , are thermal expansion coefficient, stress sensitivity factor and transient deformation coefficient, respectively. is external stress.

8. The laser transmission welding method for flexible circuit packaging according to claim 2, characterized in that: In S23, the formula for dynamically adjusting the weights of different features in the multimodal features is as follows: ,in, For the i The weight of the feature, For the i The deformation of the characteristic area, is the adjustment factor.

9. The laser transmission welding method for flexible circuit packaging according to claim 2, characterized in that: In S23, the method of dynamically adjusting the weights of different types of features in the multimodal features according to the predicted deformation amount also includes: for areas where the deformation degree exceeds the preset deformation threshold, increasing the weight of texture features; for areas where the deformation degree does not exceed the preset deformation threshold, increasing the weights of edge features and corner features.

10. A laser transmission welding device for flexible circuit packaging, characterized in that: include: A base, wherein the base is provided with a plurality of mounting holes; An absorption sheet having the same number as the mounting holes, the absorption sheet comprising a light absorbing layer and a heat conducting layer, the heat conducting layer being attached to the component to be welded, and the size of the absorption sheet being smaller than the mounting holes; and a control unit, wherein the control unit executes the steps of the laser transmission welding method for flexible circuit packaging as described in any one of claims 1 to 9, aligns the absorption sheet with the mounting hole, uses laser to sequentially irradiate the light absorbing layer, so that the light absorbing layer generates heat after absorbing laser energy, and realizes partial welding of the component to be welded and the substrate under the cooperation of the light absorbing layer and the mounting hole.

11. The laser transmission welding device for flexible circuit packaging according to claim 10, characterized in that: The laser transmission welding device also includes an infrared thermal imager and a laser displacement sensor. The infrared thermal imager and the laser displacement sensor are respectively installed at designated positions close to the welding area and are both connected to the control unit.

12. The laser transmission welding device for flexible circuit packaging according to claim 10, characterized in that: The laser transmission welding device further comprises a camera device, and a laser displacement sensor of the camera device is installed at a designated position close to the welding area and is connected to the control unit.

13. A computer storage medium, characterized in that: The computer storage medium stores a computer software product, and the computer software product includes several instructions for enabling a computer device to execute the laser transmission welding method for flexible circuit packaging as described in any one of claims 1 to 9.

Images