Ultrafine and ultrathin nano-silver paste conductive circuit processing method and system

Abstract

This invention discloses a method and system for processing ultra-fine and ultra-thin nano-silver paste conductive lines, relating to the field of circuit processing technology. The method generates a single circuit template and expands it into multiple original dispensing paths according to the number of terminals. The control system performs curvature partitioning, path point densification or simplification, and nozzle height smoothing compensation based on the three-dimensional contour. It also registers the paths with the theoretical circuit model and calculates lateral offset, line width, thickness, dispensing speed, and dispensing volume compensation. Subsequently, a hydrodynamic dispensing device is used to prepare the nano-silver paste conductive lines in segments, creating overlapping and intersecting sections of the same line in two right-angle transition areas. Finally, after pre-drying, low-temperature curing, online visual inspection, three-dimensional inspection, and resistance detection, the qualified trajectory and process parameters are written into the production data. This method can connect the front terminal pads to the back bonding pads via the side, providing a stable conductive signal path for back bonding and improving the continuity, adhesion, and batch consistency at right-angle transitions.

Description

Technical Field

[0001] This invention relates to the field of circuit processing technology, specifically to a method and system for processing ultra-fine and ultra-thin nano-silver paste conductive circuits. Background Technology

[0002] Existing display modules typically have terminal pads on the front edge of the display panel, which are then bonded to flexible circuit boards or flip-chip films via a lamination process. After bonding, the flexible circuit board needs to be folded to the back, or space needs to be reserved at the edge for bending and sealing. This method is suitable for products with wide bezels, but in products with narrow bezels, high screen-to-body ratios, and thinness, it can easily lead to problems such as large front space occupation, limited bending, and difficulty in adhesive routing.

[0003] Figure 11 In the conventional front-side terminal structure shown, the terminal pads, pressing components, and bending paths are all close to the edge of the display area. Further compression of the bezel can easily become a structural constraint. To reduce front-side footprint, the front-side terminal signals can be routed to the sides and back via conductive lines, with bonding completed on the back side. Nano-silver paste circuits have a certain degree of ductility and morphological adaptability, making them suitable for forming conductive paths on the roughened sides, such as... Figure 12 As shown, the circuit starts from the front terminal pad, passes through two right-angle transition areas, and connects to the back bonding pad.

[0004] However, the three sides of the display panel are not continuous planes. Right-angle transition areas have problems such as abrupt height changes, chamfers, burrs, roughening differences, and warping. Micron-level height errors or lateral offsets can cause broken wires, misaligned terminals, or bridging. The back-side bonding solution has obvious structural advantages, but its process window is narrower. Figure 15 This illustrates the spatial relationship of arranging the connection area on the back. If the lines can be stably led from the front to the back, the flexible line connection area can avoid the edge of the front display area, thereby reducing the front bending space and packaging allowance.

[0005] During trial production, if the planar trace coordinates are still used, and operators manually correct the height and lateral position at right angles point by point, this method is usually only suitable for a small number of samples. After changing batches of panels, the side roughening, edge chamfering, and terminal deviations change, and the original empirical parameters are easily rendered invalid. To address this, this invention integrates panel three-sided preprocessing, marked point images, three-dimensional contours, and post-processing inspection results into a single trajectory generation process. Before dispensing, a traceable compensation amount is provided, and after dispensing, the qualified trajectory and process window are saved as production data for subsequent batch recall. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for processing ultra-fine and ultra-thin nano-silver paste conductive circuits to address the shortcomings in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits, comprising: Obtain the display panel screen marking points and terminal design data, establish the workpiece coordinate system and theoretical circuit model, roughen the first right-angle transition area and the second right-angle transition area of ​​the display panel, and clean the front terminal area and the back bonding area. The image data and 3D contour data of the display panel are collected. A single line template is generated based on the screen marking points and expanded into multiple original dispensing paths according to the number of terminals and the terminal spacing. The original dispensing paths are subjected to curvature partitioning and local compensation based on the 3D contour data to obtain an optimized dispensing path. The optimized dispensing path is registered with the theoretical circuit model to generate a 3D dispensing trajectory. Nano-silver paste circuits are prepared in segments along a three-dimensional dispensing trajectory, and overlapping joints are formed in the first and second right-angle transition zones. The nano-silver paste circuits are then cured and tested. Based on the test results, the three-dimensional dispensing trajectory and process parameters are corrected to obtain the final production data.

[0008] Furthermore, the curvature partitioning process is not used in isolation to determine whether to densify path points. Instead, it uses the curvature level as a unified index, simultaneously outputting the control point step distance, nozzle target height smoothing slope, dispensing speed multiplier, and dispensing volume multiplier per unit length. The processor generates trajectory parameters and dispensing parameters based on the same curvature level, ensuring that the nozzle movement continuity changes synchronously with the amount of silver paste deposited. This avoids problems such as accumulation caused by simply reducing the speed or thinning still occurring by simply adjusting the height.

[0009] Furthermore, in the overlapping section of the first right-angle transition zone and the second right-angle transition zone, the processor reads the wet film state of the previous line segment. The wet film state includes the dispensing end time of the previous line segment, the visually estimated wet film width, the three-dimensionally estimated wet film height, or a combination thereof. Based on the wet film state, the processor calculates the reduction dispensing coefficient of the next line segment in the overlapping area, so that the overlapping area forms a continuous conductive network without exceeding the thickness threshold or encroaching on the safety distance between adjacent lines due to repeated dispensing.

[0010] Furthermore, the curing test results are not only recorded as qualified or unqualified, but are also back-calculated to the line number, line segment number, and three-dimensional trajectory point number. The processor updates the compensation table within the preset correction limit according to the anomaly type. For example, the right-angle transition area line break is mapped to the joint correction of overlap length, nozzle height, dispensing speed, and dispensing volume, and the array short circuit is mapped to the joint correction of line width compensation, dispensing volume, and lateral offset.

[0011] In one exemplary embodiment of this disclosure, image data and three-dimensional contour data of the display panel are acquired, and a single line template is generated based on screen marker points, including: The positions of at least two screen markers are acquired using a vision system, and the screen markers are mapped to the imported terminal design data. Based on the coordinate correspondence results, determine the arrangement direction of the front terminal pads, the number of terminals, the terminal spacing, and the correspondence of the back bonding pads; A single line template is generated for the corresponding front terminal pads and back bonding pads. The single line template includes a front overlap section, a first transition section, a side extension section, a second transition section, and a back bonding section. The template of a single line is copied in an array according to the terminal spacing, and the minimum spacing between adjacent lines is verified to obtain the original dispensing path of all lines.

[0012] In one exemplary embodiment of this disclosure, generating a single line template for corresponding front terminal pads and back bonding pads includes: The center line of the front terminal pad is used as the initial reference for the front overlap section, the side center line or the side preset conductive area is used as the guiding reference for the side extension section, and the center line of the back bonding pad is used as the termination reference for the back bonding section. The front overlap section and the side extension section are connected by a first transition section, and the side extension section and the back binding section are connected by a second transition section; the start and end ends of each line section are reserved with overlap allowance so that adjacent sections can form controlled overlap near right angles.

[0013] Furthermore, when performing curvature partitioning and local compensation on the original dispensing path based on the 3D contour data, the following steps are included: Select contour sampling points in the front, side, back, first right-angle transition zone, and second right-angle transition zone of the original dispensing path, and determine the curvature level of the current area based on the directional changes of adjacent contour points. Regions with high curvature levels are marked as high curvature transition regions, and regions with low curvature levels and continuous contours are marked as low curvature surface regions. In the high curvature transition zone, add path control points and reduce dispensing speed; in the low curvature surface area, merge redundant control points and maintain continuous dispensing. The distance between the nozzle and the display panel is adjusted based on the change in the height of the three-dimensional contour to obtain an optimized dispensing path.

[0014] In one exemplary embodiment of this disclosure, correcting the spacing between the nozzle and the display panel based on changes in the three-dimensional contour height includes: Obtain the local normal direction and local height corresponding to each path control point; The height difference between adjacent control points is compared with a preset height change threshold. If the height difference exceeds the preset height change threshold, a transition control point is added between the adjacent control points. Set the target height of the nozzles at each control point to the sum of the local height and the preset distance from the surface; The nozzle target height of adjacent control points is smoothed to ensure that the electrohydrodynamic dispensing nozzle maintains continuous movement when passing through the first right-angle transition zone and the second right-angle transition zone.

[0015] In one exemplary embodiment of this disclosure, the first right-angle transition area and the second right-angle transition area of ​​the display panel are roughened, and the front terminal area and the back bonding area are cleaned, including: Laser cutting or laser roughening is performed on the terminal sides of polycrystalline silicon display panels or thin-film transistor display panels to achieve a surface roughness of 1.5μm to 2.5μm. Local energy trimming is performed on the first and second right-angle transition areas to ensure a continuous transition between the roughened side area and the front terminal area and the back bonding area, respectively. Plasma cleaning is performed on the front terminal area and the back bonding area, and the path collection or dispensing process is initiated within a preset waiting time after cleaning.

[0016] In one exemplary embodiment of this disclosure, the dispensing path is optimized and registered with the theoretical circuit model to generate a three-dimensional dispensing trajectory, including: The terminal edge points, side edge points, and back bonding area edge points in the actual 3D contour data are extracted as actual feature points. The theoretical feature points corresponding to the actual feature points are extracted from the theoretical circuit model. The coordinate transformation relationship is obtained based on the actual feature points and the theoretical feature points. The original dispensing path is transformed to the actual contour position of the display panel. Based on the transformed path position, the lateral offset compensation, nozzle height compensation, dispensing volume compensation, and dispensing speed compensation for each line are calculated.

[0017] In one exemplary embodiment of this disclosure, the nano-silver paste circuit is prepared in segments along a three-dimensional dispensing trajectory, including: A front overlap segment is prepared on the front terminal pad, so that the front overlap segment covers the effective conductive area of ​​the corresponding terminal. A first transition segment is prepared along the first right-angle transition area, so that the end of the first transition segment and the front overlap segment form an interleaved overlap. A side extension segment is prepared along the side, and the side extension segment and the first transition segment are continuously conductive. A second transition segment is prepared along the second right-angle transition area, so that the end of the second transition segment and the side extension segment form an interleaved overlap. A back bonding segment is prepared on the back bonding pad, so that the back bonding segment is connected to the second transition segment and the back bonding pad.

[0018] In one exemplary embodiment of this disclosure, the overlap length of the staggered overlapping portion is 10 μm to 80 μm, the terminal spacing of the nano silver paste circuit is 50 μm to 55 μm, the line width is 30 μm to 35 μm, the thickness is 2 μm to 5 μm, the extension length of a single circuit between the front terminal pad and the back bonding pad is 0.4 mm to 0.55 mm, and the dispensing speed in the high curvature transition area is lower than the dispensing speed in the plane area where the front terminal pad is located or the plane area where the back bonding pad is located.

[0019] According to one aspect of this disclosure, an ultra-fine and ultra-thin nano-silver paste conductive circuit processing system is provided, including a positioning fixture, a vision acquisition unit, a three-dimensional contour acquisition unit, a current-driven dispensing unit, a detection feedback unit, a processor, and a memory. The memory stores a program executable by the processor. When the processor executes the program, it controls the positioning fixture, the vision acquisition unit, the three-dimensional contour acquisition unit, the current-driven dispensing unit, and the detection feedback unit to perform the ultra-fine and ultra-thin nano-silver paste conductive circuit processing method.

[0020] In this system, the vision acquisition unit, the 3D contour acquisition unit, the electrohydrodynamic dispensing unit, and the detection feedback unit do not operate independently. Instead, they are linked together through a trajectory point data table maintained by the processor. Each trajectory point includes at least spatial coordinates, curvature level, nozzle target height, target height slope, dispensing speed, dispensing amount per unit length, overlap mark, and detection write-back index. The abnormal coordinates output by the detection feedback unit update the compensation value of the corresponding trajectory point according to the detection write-back index.

[0021] The technical effects and advantages provided by the present invention in the above technical solution are as follows: 1. This invention can lead the front terminal PAD to the back bonding PAD, providing a conduction signal path for the back bonding, which helps to reduce the bending radius and frame width of the FPC; 2. Before generating the trajectory, this invention reads the actual outline of the panel and adjusts the control point density, nozzle height, speed, and adhesive output according to the curvature difference. At two right-angle transitions, staggered overlapping is used to prevent thinning or breakage of the silver paste lines during cross-surface transitions. The test results, after being written back, can be used as subsequent production parameters, thereby reducing the number of manual adjustments per panel and improving the dimensional and resistance consistency of products in the same batch.

[0022] 3. The invention uses homogeneous parameter mapping and closed-loop control to enable multiple process variables to change collaboratively around the same abnormal risk, rather than making isolated corrections to the path, glue dispensing and detection. Therefore, it can better reflect the overall technical effect of forming micro-circuits in the right-angle transition zone.

[0023] The above effects are used to illustrate the main process benefits of the present invention. The specific parameter range can still be matched and adjusted according to the display panel material, edge morphology, silver paste system and dispensing equipment capabilities. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0025] Figure 1 This is a flowchart of a method for fabricating ultra-fine and ultra-thin nano-silver paste conductive circuits according to the present invention; Figure 2 This is a schematic diagram of the nano-silver paste conductive circuit structure with overlapping front, side and back surfaces of the display panel in this invention; Figure 3 This is a diagram of the visual registration, trajectory compensation, and detection feedback architecture in this invention; Figure 4 This is a schematic diagram illustrating the application scenario of the back pads in this invention; Figure 5 This is a schematic diagram of the display panel clamping and positioning and the establishment of the workpiece coordinate system in this invention; Figure 6 This is a schematic diagram of the three-sided pretreatment process in this invention; Figure 7 This is a schematic diagram of single-line template generation and array expansion in this invention; Figure 8 This is a schematic diagram of curvature partitioning and path point density adjustment in this invention; Figure 9 This is a schematic diagram of theoretical model registration and dispensing compensation calculation in this invention; Figure 10 This is a schematic diagram illustrating the closed-loop data processing of pilot-scale testing and mass production in this invention. Figure 11 This is a schematic diagram of the conventional pad conduction structure in low-temperature polycrystalline silicon. Figure 12 A schematic diagram of a three-sided conductive circuit using nano-silver paste. Figure 13 A roughened 3D contour detection map of the side area of ​​the display panel; Figure 14 A roughened micrograph of the side area of ​​the display panel; Figure 15 This is a schematic diagram of a low-temperature polysilicon back pad solution. Detailed Implementation

[0026] The processing flow of the present invention will be described below with reference to the accompanying drawings and embodiments. The drawings are used to illustrate the cooperation relationship between terminals, sides, transition areas, and detection feedback. The same or similar markings in the drawings correspond to the same or similar structures. The layout of the actual equipment, sensor model, and fixture type can be appropriately adjusted according to the production line conditions.

[0027] Although relative terms such as "up" and "down" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples shown in the accompanying drawings. It is understood that if the device of the icon is flipped upside down, the component described as "up" will become the component described as "down." When a structure is "up" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.

[0028] The terms “a,” “one,” “the,” and “the” are used to indicate the existence of one or more elements / components / etc.; the terms “include” and “have” are used to indicate an open-ended meaning of inclusion and that other elements / components / etc. may exist in addition to the listed elements / components / etc.

[0029] The present invention will be further described below with reference to specific embodiments; for ease of understanding, the following embodiments are illustrated using a low-temperature polycrystalline silicon display panel as an example, but the method is also applicable to thin-film transistor display panels and other screens with similar terminal structures; unless otherwise stated, the following dimensions, thresholds and process windows can be equivalently adjusted according to the actual product material, thickness, terminal spacing, silver paste viscosity and equipment capabilities.

[0030] It should be noted that in this article, "front" refers to the side with terminal pads or display driver connection structure, "back" refers to the side to be back-bonded, and "side" refers to the terminal edge surface of the display panel; the first right-angle transition area is located between the front and the side, and the second right-angle transition area is located between the side and the back.

[0031] Example 1: The processing method provided in this example is used to form nano-silver paste conductive lines between the front terminal pads, side pads, and back bonding pads of a display panel. It shows the basic structure of the three-sided overlapping conductive lines. The nano-silver paste conductive lines are divided into a front overlapping section, a first transition section, a side extension section, a second transition section, and a back bonding section according to their spatial position. The first transition section crosses the first right-angle transition area, and the second transition section crosses the second right-angle transition area. Figure 2 As shown.

[0032] Since the surface morphology of the right-angle transition zone is prone to abrupt changes, if the entire line is applied with high-speed glue in a single continuous path, the silver paste may be thinned, accumulated, or deviated from the center at the edge. Therefore, this embodiment provides staggered overlapping joints at the ends of adjacent segments. The position of these joints is preferably near the transition zone, but they do not press into the insulation distance between adjacent lines. Their length can be set according to the line width, silver paste leveling, and terminal spacing.

[0033] The processing system may include a positioning fixture, a vision acquisition unit, a three-dimensional contour acquisition unit, a current-powered dispensing unit, a detection feedback unit, a processor, and a memory. The vision acquisition unit is used to acquire the marking points, terminal edges, and circuit morphology. The three-dimensional contour acquisition unit is used to acquire the height data of the sides and the two right-angle transition areas. The dispensing unit is used to execute the three-dimensional dispensing trajectory. The detection feedback unit is used to judge the appearance, size, resistance, and continuity status of the cured circuit.

[0034] Figure 3 The data relationships between the units are illustrated. Design data, visual data, and 3D contour data are input into the processor in parallel. The processor first performs feature registration, then curvature partitioning and compensation calculation, and then sends the trajectory to the dispensing unit. The detection feedback unit sends the detection results back to the processor, enabling the processor to correct lateral offset, nozzle height, dispensing volume, dispensing speed, and overlap length.

[0035] In back-bonding applications, the front terminal signals of the display panel are guided to the back-bonding pads via nano-silver paste conductive lines. Figure 4 In the structure shown, the flexible circuit connection area on the back no longer occupies the main space of the front display edge, and the overall structural design can leave more space for the display area, sealing edge or support structure.

[0036] In actual production, the position of the back bonding pads can be determined according to the product stack-up and connector orientation. For products with a large number of terminals, multiple lines can be arranged according to the terminal spacing. For products that require shielding or avoidance in certain areas, local detours can be introduced in the side extension section. However, the safety distance between adjacent lines after the detour still needs to be verified by the system.

[0037] Example 2: Before applying adhesive, the display panel to be processed is fixed on the positioning fixture. The fixture can be selected from one or more combinations of vacuum adsorption, edge limiting, positioning pins, and elastic pressure blocks according to the panel size. For panels with thin glass substrates, low edge strength, or local warping, it is preferable to use partitioned adsorption and control the clamping force to ensure that the terminal edges are stably attached to the support surface, while avoiding new edge chipping, cracks, or residual stress caused by clamping.

[0038] The vision acquisition unit acquires at least two screen marker points on the display panel. To improve the reliability of rotation and scale correction, it is preferable to acquire three or four marker points, and abnormal marker points are discarded or downweighted. After marker point recognition, the processor matches the recognized coordinates with the design coordinates, calculates the translation, rotation angle, scaling factor, and necessary nonlinear corrections, thereby establishing the workpiece coordinate system and defining the relationship between the positioning fixture, panel marker points, and coordinate directions. Figure 5 As shown.

[0039] After the workpiece coordinate system is established, the control system imports the design data of the front terminal pads, the back bonding pads, the side and the two right-angle transition areas. The design data can come from the product circuit diagram, the terminal layout diagram or the processing file that the equipment can recognize. When importing, the system does not directly use the design coordinates as the final motion coordinates, but first converts them into a theoretical circuit model.

[0040] The theoretical circuit model should include at least the following: the front terminal number, the back bonding pad number, the terminal center line, the target line width, the target thickness, the segment boundary, the overlap length, the recommended speed, the recommended glue dispensing amount, and the allowable offset range for each circuit. If a terminal is set as a reserved terminal, an unsoldered terminal, or a test terminal, the system can mark its circuit as unprocessed or processed separately when expanding the array.

[0041] During the clamping and positioning process, the system can also perform a pre-check of panel flatness. If the overall tilt of the panel exceeds the compensation range of the equipment, or if there is obvious chipping near the right-angle edge, the system can provide a prompt to re-clamp or reject the panel. This can prevent the panel from being found to be defective in the subsequent high-value dispensing process.

[0042] Example 3: The purpose of three-sided pretreatment is to improve the wetting, adhesion and continuous forming conditions of nano silver paste on different surfaces. Unlike planar printing, the key areas of the three-sided circuit are concentrated on the sides and two right-angle transition areas. If the sides are too smooth, the silver paste is prone to shrinkage or desorption before curing. If the roughening is too deep, the edge of the circuit is prone to spread along the groove, resulting in unstable line width. Therefore, it is necessary to control the roughening intensity and cleaning sequence.

[0043] Figure 6 The process flow for three-sided pretreatment is given. First, the edges of the sides are trimmed or roughened by laser cutting to form micro-undulations suitable for silver paste adhesion on the roughened surface. Then, the first right-angle transition area and the second right-angle transition area are locally energy trimmed to prevent the connection between the roughened area of ​​the side and the front and back sides from being too sharp. Finally, plasma cleaning or other dry cleaning is performed on the front terminal pads and the back bonding pads.

[0044] In a preferred embodiment, the roughened surface roughness of the side is controlled between 1.5 μm and 2.5 μm. This range can be adjusted according to the particle size of the silver paste, the resin system, and the curing conditions. If the original cutting quality of the panel side is good, low-energy multiple scans can be used to reduce the thermal impact. If there are obvious cutting stripes on the side, deburring scans can be performed first, followed by uniform roughening scans.

[0045] The first right-angle transition zone is close to the front terminal pads. During roughening, the goal is to avoid encroaching on the effective conductive area of ​​the terminals. The second right-angle transition zone is close to the back bonding pads. During processing, it is necessary to maintain a sufficiently flat bonding surface to avoid uneven stress caused by local silver paste build-up or edge protrusions during lamination. Both transition zones can be trimmed using small spot size, low energy, or defocus scanning to create a gentler transition between the roughened sides and the front and back sides.

[0046] The cleaning step is preferably scheduled after roughening, and a waiting time is specified after cleaning. For example, if the glue is not applied after the preset waiting time has elapsed after cleaning, the system can require re-cleaning or at least re-inspection of the terminal surface condition. This can reduce the impact of airborne particles, adsorbed moisture and organic contaminants on the adhesion of silver paste. The final processing results are shown in Table 1.

[0047] Table 1: Objects and uses of three-sided preprocessing

[0048] The processing order in Table 1 is not mechanically fixed. For some display panels that are sensitive to certain materials, dry purging or low-temperature baking can be added after laser roughening. For products with protective films on the terminal surface, cleaning and data collection can be performed after removing the film. The core requirement is that the front, side, back and two transition areas have identifiable, recordable and repeatable surface states before entering the path calculation.

[0049] Example 4: After preprocessing, the vision acquisition unit first acquires images of the front terminal pads, the back bonding pads, and the screen marking points; the 3D contour acquisition unit then performs height scanning on the sides, the first right-angle transition area, and the second right-angle transition area. The contour acquisition device can be of the form of line laser, structured light, white light confocal, laser confocal, etc., as long as its lateral resolution and height resolution meet the requirements of the micro-line compensation calculation.

[0050] All types of collected data must first be normalized to the same workpiece coordinate system. The processor establishes a front coordinate reference using the screen marking points, and then uses the equipment calibration matrix to transform the side and back contour data to this coordinate reference. When multiple sensors are used in combination, installation deviations should also be corrected using calibration blocks or standard samples to prevent misalignment between visual coordinates and contour coordinates in the transition zone.

[0051] The results of the 3D contour detection after side roughening are as follows Figure 13 As shown, this figure does not limit the specific sensor type, but rather expresses the measurable micro-undulations of the side after coarsening. The processor can use these contour points to calculate local height, local normal, orientation change, and curvature level. Figure 14 The microstructure after side roughening provides a basis for wetting and mechanical bonding of the nano silver paste. However, the larger the undulation, the better. If the trench is too deep, the silver paste may accumulate in the depression before curing, resulting in insufficient thickness at the center of the circuit or rough edges. If the undulation is too small, the circuit is easy to peel off during bending, wiping or thermal cycling after curing.

[0052] The system can evaluate the quality of contour points, including whether the sampling density is sufficient, whether there are large areas of shadow, whether there are abnormal peaks, whether the side boundaries are clear, and whether the right-angle transition area is continuous. If local data is missing, the system can trigger secondary acquisition. If the secondary acquisition is still insufficient, interpolation can be performed based on adjacent contours. However, the interpolated areas should have a higher inspection weight in subsequent detection.

[0053] In one alternative algorithm, the system first performs median filtering on the 3D contour to remove isolated spikes, and then uses local least squares plane fitting to calculate the normal. For the normal angle and height difference between adjacent sampling points, they are compared with angle thresholds and height thresholds, respectively. If the thresholds are exceeded, the region is marked as a morphological change region. The morphological change region is not necessarily an unprocessable region, but its path control point density and nozzle height smoothing strategy should be different from those of the planar region.

[0054] When the height fluctuation of the roughened area on the side exceeds the preset upper limit, the processor first records the abnormal location and fluctuation amplitude, and then handles it according to the risk level: for abnormalities affecting the conduction path, it prompts for re-roughening or panel replacement; for abnormalities located in non-critical areas, processing can continue after reducing the dispensing speed and increasing the detection weight; for areas with local protrusions or gaps close to the center of the line, the trajectory is adjusted to avoid them or the effective line width is reduced. The above strategies are confirmed by process engineers and written into the parameter table during the verification phase.

[0055] Example 5: After obtaining the terminal image and contour data, the processor generates a single line template based on a set of corresponding front terminal pads and back bonding pads. The template consists of a front overlap section, a first transition section, a side extension section, a second transition section, and a back bonding section: the front overlap section covers the effective conductive area of ​​the front terminal, the first transition section leads the line to the side, the side extension section transmits signals along the side, the second transition section then leads the line to the back, and the back bonding section is connected to the back bonding pads.

[0056] The process of expanding a single line template and its array is as follows: Figure 7As shown, when the template is generated, the system does not only save the geometric polyline, but also saves the process attributes of each segment, including dispensing sequence, speed level, dispensing volume level, control point density, overlap position and allowable compensation range. When the array is expanded, the above process attributes are copied along with the line. The segmented control of a single line template is shown in Table 2.

[0057] Table 2: Segmented Control of Single Line Templates

[0058] The initial reference of the template can be determined by three center lines: the first is the center line of the front terminal pad, which serves as the positioning reference for the front overlap section; the second is the center line of the side or the center line of the preset conductive strip, which serves as the guiding reference for the side extension section; and the third is the center line of the back bonding pad, which serves as the termination reference for the back bonding section. The three center lines are connected by transition sections, which can be polylines, arc splines, or three-dimensional curves generated according to the actual contour.

[0059] During array expansion, the system replicates a single line template according to the terminal spacing. For structures with a terminal spacing of 50μm to 55μm and a target line width of 30μm to 35μm, the insulation spacing between adjacent lines is small. Therefore, minimum spacing verification is required after replication. If the spacing is insufficient in a certain area due to lateral compensation, the system will prioritize adjusting the lateral offset of the transition section or local line width compensation, rather than arbitrarily changing the alignment relationship of the terminal centers.

[0060] When the back bonding pads and the front terminal pads are not aligned one-to-one, a horizontal transition section can be added to a single line template. The horizontal transition section should be placed in a low curvature area and avoid two right-angle transition areas as much as possible. If a horizontal transition must be made on the side, the system should reduce the speed and re-verify the spacing between adjacent lines to prevent multiple lines from converging on the side and causing a short circuit risk.

[0061] Example 6: Curvature partitioning is an important step that distinguishes this invention from ordinary planar dispensing. The system extracts three-dimensional contour sampling points along the original dispensing path and determines the morphology level of the current path segment based on the direction change, normal change, and height difference of the sampling points. The front terminal area, the middle of the side, and the back bonding area are usually low curvature surface areas, while the first right-angle transition area and the second right-angle transition area are usually high curvature transition areas. Local chipping, burr shadows, or missing sampling locations can be marked as local abnormal areas.

[0062] In low-curvature areas, the system can merge redundant control points to ensure stable and continuous nozzle operation. In high-curvature transition areas, the system adds path control points and sets speed buffers, allowing the nozzle to gradually decelerate before entering the right-angle position and then gradually restore its surface velocity after passing through the right-angle position. Figure 8 As shown.

[0063] The path point density can be determined using the following logic: when the directional angle between adjacent contour points is less than the first threshold and the height difference is less than the first height threshold, a longer step size is allowed in this area. When the directional angle or height difference exceeds the threshold, a transition control point is inserted between adjacent control points. When a local abnormal point is detected, it is first determined whether the abnormal point is isolated noise. If it is noise, it is filtered out. If it is a real edge abrupt change, the area is divided into a local abnormal area.

[0064] The nozzle height sequence and path control points are generated simultaneously. For each control point, the processor reads its local height and normal direction, and calculates the nozzle target height according to the set distance from the surface. In the first and second right-angle transition zones, if the adjacent target heights change too quickly, a transition is made through moving average, spline interpolation, or slope limitation to ensure continuous nozzle rise and fall and avoid silver paste breakage, accumulation, or nozzle scraping caused by instantaneous jumps.

[0065] In a preferred embodiment, the dispensing speed in the high curvature transition zone is lower than that in the low curvature surface zone, and the speed change adopts a trapezoidal or S-shaped transition. Reducing the speed can increase the dispensing stability per unit length and allow the silver paste more time to wet the roughened surface. However, too low a speed may also cause accumulation. Therefore, it needs to be determined in conjunction with the dispensing volume and overlap length.

[0066] In a parameterized implementation, the processor establishes a parameter vector P=(d, S, V, Q) for each trajectory point, where d is the control point step distance, S is the upper limit of the smooth slope of the nozzle target height, V is the dispensing speed, and Q is the amount of adhesive dispensed per unit length. The higher the curvature level, the smaller d, the lower S, and the lower V; Q does not simply increase linearly with speed, but is synchronously corrected in conjunction with the target line width, target thickness, and overlap markings.

[0067] Table 3: Example of co-mapping between curvature partitioning results and trajectory / expansion parameters

[0068] By mapping in Table 3, the same curvature judgment result can simultaneously control kinematic parameters and material deposition parameters, thus avoiding the side effects of individually densifying path points, individually reducing speed, or individually adjusting height. For example, if only the speed is reduced in a high curvature area without reducing the amount of adhesive dispensed, it is easy to accumulate at the overlap. If only the amount of adhesive dispensed is reduced without reducing the slope of height change, edge breakage may still occur.

[0069] Example 7: After completing the curvature partitioning, the processor registers the optimized dispensing path with the theoretical circuit model. This registration does not simply perform translation correction on the entire circuit group, but rather compares the features of the terminal edges, side edges, back bonding area edges, and right-angle transition areas separately, so that the corresponding positions in the theoretical model fall on the actual panel outline. For specific mapping relationships, please refer to... Figure 9 .

[0070] Registration can be divided into coarse registration and fine registration. Coarse registration completes global coordinate transformation based on the screen marking points, mainly correcting translation, rotation and scale errors. Fine registration completes local correction based on terminal edge points, side edge points, back bonding pad edge points and right angle transition area feature points. For panels with slight edge curvature, fine registration can use partitioned affine, thin plate spline or local weighted transformation.

[0071] After registration, the processor generates compensation amounts for each line: lateral compensation is used to correct the deviation between the line center and the effective area of ​​the terminal; nozzle height compensation is used to maintain a stable distance from the surface; speed compensation is used to adapt to the forming differences between the planar area and the high curvature area; and glue output compensation is used to control the line width and thickness. If necessary, line width and thickness target corrections can also be superimposed to meet the requirements of resistance, bonding, and insulation spacing.

[0072] When calculating the adhesive amount compensation, the system can use the target cross-sectional area as an intermediate variable. If the target line width of a certain road segment is w and the target thickness is t, the target cross-sectional area can be approximated by multiplying w by t and then by the shape correction factor. The shape correction factor is related to the surface tension of the silver paste, the degree of roughening and curing shrinkage, and can be calibrated in the verification stage. The control system converts the target cross-sectional area into the adhesive amount per unit length and generates dispensing control commands in combination with the speed.

[0073] When calculating lateral offset, the system needs to consider the effective width of the terminal and the spacing between adjacent lines. If a line offsets to one side and compresses the spacing between adjacent lines, the system can make coordinated adjustments to the line and adjacent lines. Coordinated adjustments should preferably occur on the side or in the transition area and should not disrupt the electrical connection between the front terminal pads and the back bonding pads.

[0074] Specifically, the steps of the three-sided path compensation and trajectory generation algorithm are as follows: A1. Read the screen marking points, terminal design data and three-dimensional contour data, and unify the data into the workpiece coordinate system; A2. Select a set of front terminal pads and back bonding pads to generate a single line template containing five line segments; A3. Copy the template for a single line according to the terminal spacing, and verify the minimum safe distance between adjacent lines; A4. Extract local contour points along each line, and divide them into low curvature surface areas, high curvature transition areas, and local anomaly areas based on changes in direction, normal, and height. A5. Insert transition control points in the high curvature transition zone, merge redundant control points in the low curvature surface zone, and maintain the sequential connection relationship between line segments. A6. Generate a nozzle height sequence based on the local height of each control point and the target distance from the surface, and smooth adjacent heights; A7. Write the lateral offset, dispensing speed, dispensing volume, target line width, and nozzle height into the trajectory points to output the three-dimensional dispensing trajectory; A8. Update the compensation table based on the test feedback and call it in the next round of trial production or mass production fine-tuning.

[0075] Example 8: A conductive circuit of nano-silver paste was prepared along a three-dimensional dispensing trajectory using an electrohydrodynamic dispensing unit. Before dispensing, the system preferably performed a test spray check. The test spray check included the continuous dispensing status, initial line width, breakpoints, and nozzle contamination. If the test spray line width deviated significantly from the target range, the system would not proceed to the formal panel dispensing but would instead prompt for cleaning the nozzle, adjusting the driving voltage, or replacing the silver paste.

[0076] During formal dispensing, the system proceeds in the following order: front overlap section, first transition section, side extension section, second transition section, and back bonding section. The front overlap section should cover the effective conductive area of ​​the front terminal pads, but its edge should not exceed the safety insulation boundary of the adjacent terminals. Before the first transition section enters the first right-angle transition zone, the nozzle speed is reduced, and the nozzle height is corrected point by point according to the contour of the transition zone.

[0077] The overlapping section refers to the controlled overlap length at the ends of adjacent line segments. Taking the front overlap section and the first transition section as an example, the starting part of the first transition section can cover a distance of the end of the front overlap section, so that the two line segments form a continuous conductive area before and after the right angle. The overlap length is preferably 10μm to 80μm, and the specific value can be determined according to the line width, thickness, silver paste leveling and transition area roughness.

[0078] On the side extension section, the system adjusts the speed and glue dispensing amount according to the roughness and height fluctuation of the side. If the local roughening depth is large, the speed can be reduced appropriately to fill the micro-undulations with silver paste. If the local roughening is shallow or close to the adjacent line, the glue dispensing amount can be controlled to avoid the line width from expanding outward. The second transition section and the side extension section also form an overlapping joint. Then the back bonding section covers the effective connection area of ​​the back bonding pad.

[0079] In a preferred process window, the terminal spacing of the nano-silver paste conductive lines is 50μm to 55μm, the line width is 30μm to 35μm, the thickness after curing is 2μm to 5μm, and the length of a single line extending from the front terminal pad through the side to the back bonding pad is 0.4mm to 0.55mm. The above dimensions can be adjusted according to the product structure, as shown in Table 4, but the adjusted dimensions should still meet the requirements for insulation spacing between adjacent lines and back bonding reliability.

[0080] Table 4: Dispensing Control Items and Optimal Range

[0081] To avoid excessive thickness in some areas of the overlap, the system can use a method of decreasing glue dispensing or shortening the pulse width in the overlap area. When the first section of the circuit already has a certain amount of wet film, the subsequent section of the circuit does not need to be dispensed with the normal amount of glue at the overlap. This can form a continuous conductive network and reduce the risk of short circuits and bonding interference caused by the stacking at the overlap.

[0082] Specifically, after the previous line segment is dispensing adhesive, the processor writes its end time t0, theoretical wet film height h0, visually estimated wet film width w0, and solid content shrinkage coefficient of that segment into the overlap status table. When the next line segment enters the same overlap area, the reduction dispensing coefficient is calculated according to K=K0·f(Δt,h0,w0), where Δt is the difference between the current time and t0, and K0 can be between 0.55 and 0.85. When Δt is short and the wet film height is high, K takes a lower value; when the wet film is partially dry or the height is insufficient, K takes a higher value to balance continuous conduction and overlap stacking height control.

[0083] For the current-mode pulse dispensing method, reduced dispensing volume can be achieved by reducing the pulse duty cycle, shortening the pulse width, or reducing the local liquid supply drive. For the continuous dispensing method, reduced dispensing volume can be achieved by reducing the supply volume or increasing the instantaneous speed of the overlap area. Regardless of the method used, the thickness of the overlap area after curing should preferably not exceed 1.3 times the average thickness of the adjacent non-overlap areas, and the outward expansion width of the overlap area should not intrude into the safety insulation distance of adjacent lines.

[0084] When multiple lines are processed in parallel, either complete path processing or segmented batch processing can be used. Complete path processing helps maintain the continuity of the same line, while segmented batch processing helps to uniformly control the environment and speed in the same area. Regardless of the strategy used, the system should record the actual processing sequence of each line so that the abnormal location can be accurately identified during detection feedback.

[0085] Example 9: After dispensing, the nano-silver paste circuitry is pre-dried and cured at a low temperature. Pre-drying is mainly used to remove some solvent and fix the wet film outline, while low-temperature curing is used to promote contact between silver particles and form a conductive network. The pre-drying temperature can be set to 60°C to 120°C, and the low-temperature curing temperature can be set to 120°C to 180°C. For different silver paste systems, pulsed light, infrared, hot air, or segmented heating methods can also be used to balance circuit resistance, adhesion, and panel heat resistance.

[0086] Table 5: Equipment, materials, curing, and testing parameters for a set of reproducible examples

[0087] The above parameters are used to illustrate a reproducible example; when changing the silver paste system, display panel thickness, terminal pitch or nozzle specifications, recalibration can be performed while maintaining the principles of "curvature zone synchronous control of trajectory and glue output, reduction of overlap area according to wet film state, and detection of abnormalities and back calculation of trajectory points".

[0088] Curing parameters should take into account circuit resistance, adhesion, and heat resistance of the display panel. If the curing temperature is too low or the time is insufficient, the circuit resistance may be too high. If the temperature is too high or the temperature rises too quickly, thermal stress may be generated on the edge structure of the display panel, and microcracks may be generated at the overlap due to uneven shrinkage. Therefore, the curing curve should be confirmed on the verification panel before it is used for mass production.

[0089] The detection feedback unit can consist of visual inspection, 3D inspection, and electrical inspection. Visual inspection focuses on identifying line width, broken lines, excess adhesive, misalignment, and surface contamination; 3D inspection is used to measure the cured thickness, overlap height, and right-angle edge height; electrical inspection is used to determine resistance, open circuits, and short circuits. In addition to providing a pass / fail judgment, the detection data also records the line number, abnormal area, abnormality type, and its corresponding trajectory point number, facilitating subsequent parameter write-back.

[0090] When correcting anomalies, the system first determines the cause based on the location and detection value of the anomaly, and then modifies the corresponding parameters. For example, when there is a break in the right-angle transition zone, the system prioritizes checking the overlap length, nozzle height above the surface, transition zone speed, and roughening status; when the local thickness is too high, the system prioritizes checking the glue output per unit length, speed setting, and whether the overlap reduction is effective.

[0091] After a correction, the system can be re-tested to verify the circuit. If the same anomaly occurs repeatedly, it indicates that the problem may not be caused by a single parameter, but rather by a systematic deviation in panel pretreatment, silver paste batch, or printhead condition. In this case, batch processing should be suspended to reconfirm the side roughening profile, cleaning status, printhead coaxiality, adhesive dispensing stability, and curing equipment temperature uniformity.

[0092] For mass production testing results, the system can be configured with tiered responses. For example, if a single line occasionally deviates but its resistance is within acceptable limits, it can be recorded as an observation item. If multiple lines deviate in the same direction, they should be immediately re-registered. If multiple panels experience line breaks in the same transition zone, the verification process should be returned to adjust the overlap and height compensation. Example 10: Before formal mass production, it is preferable to select a verification panel to perform the complete process. The verification panel can be a sample with the same structure as the mass production panel, or a process verification panel that retains the same terminal spacing, side thickness, and back bonding structure. The purpose of verification is not only to prove that a single panel can be successfully processed, but also to determine the process window, that is, under allowable panel differences, environmental changes, and silver paste batch variations, the lines can still meet the requirements for line width, thickness, resistance, and reliability.

[0093] Verification Example 1: To illustrate the aforementioned synergistic control effect, verification samples with terminal spacing of 50μm to 55μm, target linewidth of 30μm to 35μm, and target thickness of 2μm to 5μm were selected for control trials. All groups used the same nano-silver paste and curing conditions, only changing the path compensation, overlap method, coarsening conditions, or segmentation strategy. The following data are illustrative verification data and can be replaced by the applicant's measured statistical values ​​before formal submission.

[0094] Table 6: Comparison Results of 2D Path, 3D Compensation, Overlap, Coarsening, and Segmentation Strategies

[0095] Table 7: Impact of different overlap lengths on conduction and short-circuit risk in the right-angle transition zone

[0096] As shown in Tables 6 and 7, using three-dimensional compensation alone, setting overlapping alone, or adjusting coarsening alone can improve some indicators. However, under the narrow spacing condition of 50μm to 55μm terminal spacing, simultaneous improvement of breakage rate, short circuit rate, resistance dispersion, and adhesion requires the combined effect of three-dimensional contour compensation, 1.5μm to 2.5μm coarsening, segmented staggered overlapping, wet film reduction of adhesive discharge, and detection feedback compensation table.

[0097] After the verification panel trial production, the detection feedback unit outputs the abnormal location and detection value. The processor corrects the path or parameters according to the abnormality type. After multiple rounds of trial production are successful, the contour data, trajectory data, dispensing parameters, curing parameters, and detection thresholds are saved as the final production data. Figure 10 As shown.

[0098] The final production data includes at least: the reference contour data of the display panel, the three-dimensional control points of each line, the segment boundary of each line segment, the target height of the nozzle, the dispensing speed, the driving voltage, the pulse frequency, the amount of adhesive dispensed per unit length, the overlap length, the pre-drying parameters, the low-temperature curing parameters, and the detection and judgment threshold. For production lines that need to be traced, the silver paste batch, nozzle number, ambient temperature and humidity, fixture number, and equipment calibration version can also be recorded.

[0099] During mass production, the system calls the final production data and makes fine adjustments based on the marker points and local contour deviations of each display panel. The fine-tuning range should be limited to the parameter window determined during the verification phase. For example, lateral offset can be corrected within a few micrometers, and nozzle height can be corrected according to local height changes, but line width, overlap length, and speed should not exceed the verified safety range.

[0100] When the same type of abnormality occurs repeatedly during mass production, the system can pause subsequent processing and send the outline, image and test results of the abnormal panel back to the verification process. Process personnel can determine whether the problem comes from panel cutting, side roughening, terminal contamination, silver paste viscosity, nozzle wear or curing equipment. If necessary, the final production data can be updated and the process window can be relocked.

[0101] Example 10: To facilitate deployment on different equipment platforms, this example breaks down the control logic into several processing steps. This logic can be executed independently by the device processor or jointly by the host computer software and the motion controller. Input data includes terminal design data, screen marker coordinates, image recognition results, 3D contour data, equipment calibration parameters, and verified process windows. Output data includes 3D dispensing trajectory, control parameters for each line segment, and detection judgment rules.

[0102] The system performs grayscale correction, edge enhancement, and terminal area recognition on the image data, and performs noise reduction, defect compensation, and coordinate unification on the 3D contour data. If the deviation between the recognized terminal edge and the design edge exceeds the threshold, the dispensing trajectory will not be generated temporarily. Instead, the system will prompt for verification of terminal contamination, image focal length, lighting conditions, or clamping status.

[0103] The marker points, terminal edge points, side edge points, and back bonding pad edge points in the design model are mapped to the corresponding features actually collected. The mapping relationship can be achieved by nearest neighbor search, constraint matching, or semi-automatic matching after manual confirmation. For locally missing features, the location can be predicted using nearby terminals, but the predicted location should be carefully verified during the inspection stage.

[0104] Sample along the line template at a set step size, and read the height, normal direction and curvature level in the neighborhood of each sampling point; when the sampling point is located in the high curvature transition zone, insert control points and reduce speed; when the sampling point is located in the low curvature surface area, merge approximately collinear redundant points; when the sampling point is located in the local anomaly area, call the corresponding avoidance, speed reduction or verification strategy.

[0105] The system calculates the amount of adhesive dispensed per unit length based on the target line width, target thickness, and local morphology. Then, it generates control commands based on the nozzle speed. For overlapping sections, the system can reduce the amount of adhesive dispensed in the next section based on the wet film state of the existing line segment, so that the overlap is both continuous and does not become excessively high.

[0106] The abnormal coordinates output by the detection feedback unit are mapped to specific trajectory points: if the broken line is located in the first right-angle transition zone, the speed, nozzle height, and overlap length of the first transition section are adjusted first; if the offset occurs in the front overlap section, the registration of the marker points and the identification of the terminal edges are checked first; if the short circuit occurs in the middle of the array, the line width compensation is reduced or the local glue dispensing is reduced first. This write-back process can be performed according to the following steps: B1. Read the visual inspection results, three-dimensional height results, and electrical inspection results for each line; B2. Establish an anomaly index according to the line number and trajectory point number, and classify the anomalies into risks such as disconnection, offset, accumulation, short circuit or attachment. B3. Based on the area where the anomaly is located, call the corresponding correction rules. In the high curvature transition area, prioritize the correction of overlap length, speed and nozzle height. In the low curvature surface area, prioritize the correction of lateral offset and dispensing volume. B4. Set an upper limit for the correction amount. If the correction amount exceeds the verification process window, stop automatic correction and prompt for manual review. B5. Use the corrected trajectory and parameters for the next verification panel or the next round of trial production, and compare the test results before and after the correction. B6. When the continuous trial production results meet the qualification standards, lock the corresponding trajectory, compensation table and process window, and generate or update the final production data.

[0107] B7. The detection feedback unit performs nearest neighbor matching between the abnormal coordinates (x,y,z) and the three-dimensional trajectory point set, and determines the trajectory point to which the abnormal belongs by combining the line number, line segment number and dispensing timestamp; when the abnormal spans multiple trajectory points, the abnormal length or area is assigned multiple weight values ​​according to the distance between trajectory points.

[0108] B8. The processor calls the limit correction matrix M according to the exception type, and prioritizes mapping the wire breakage exception to the height, speed, overlap length and glue amount correction, prioritizes mapping the short circuit exception to the line width, lateral offset and glue amount correction, and prioritizes mapping the stacking exception to the overlap reduction coefficient and speed correction; each correction shall not exceed the single correction limit set in the verification process window.

[0109] B9. The updated compensation table should include at least the line number, trajectory point number, curvature level, lateral offset, nozzle height increment, speed multiplier, dispensing volume multiplier per unit length, overlap length, overlap reduction coefficient, anomaly type, and correction version number, so that it can be called and traced in the next panel.

[0110] Through the above process, the test results are no longer just a record of the pass rate, but are transformed into executable trajectory corrections and process parameter changes; therefore, operators can trace the location of abnormalities, determine the cause, and take corrective actions, which is more suitable for the batch stable processing of ultrafine nano silver paste circuits.

[0111] Example 11: The specific type of 3D contour acquisition device is not limited, as long as it can measure the height changes of the side and the two right-angle transition zones within the target accuracy, it can be used in this method. For transparent or highly reflective panel edges, the effectiveness of edge contour data can be improved by adjusting the incident angle, adding polarization components, using confocal measurement, or setting up auxiliary calibration areas in non-functional areas.

[0112] This invention does not limit the specific formulation of the nano silver paste. The silver paste can be thermosetting, photo-sintering, or low-temperature sintering, as long as its viscosity, particle size, and curing shrinkage can meet the target linewidth, thickness, and adhesion requirements. The yield compensation, curing curve, and overlap reduction coefficient corresponding to different silver paste formulations should be recalibrated during the verification stage.

[0113] The electro-hydraulic dispensing unit can adopt continuous mode, pulse mode, or a combination mode that switches according to road segment. For the front overlap section and the back bonding section, stable continuous dispensing can be used. For the two right-angle transition areas, higher control point density and finer pulse control can be used. For the side, constant speed or variable speed control can be selected according to the roughness condition.

[0114] This method still applies even if some products have chamfered sides instead of strict right angles. In this case, curvature partitioning will identify the chamfered area as a medium-to-high curvature area, and the system can adjust the control point density and speed accordingly without changing the overall template, registration, and feedback logic. If the arrangement direction of the back-side bonding pads is different from that of the front-side terminal pads, a lateral transition section or group transition section can be added to the template of a single line. After adding the transition section, the system should still ensure that each line has a clear overlap relationship between the two transition areas and ensure that the center of the final back-side bonding section is aligned with the center of the corresponding pad.

[0115] In summary, this invention, based on clamping and positioning and three-sided preprocessing, combines image recognition, 3D contour acquisition, circuit templates, curvature partitioning, model registration, compensation calculation, segmented dispensing, staggered overlapping, curing detection, and feedback correction to enable nano-silver paste circuits to extend from the front terminal pads across the sides to the back bonding pads. This solution balances narrow bezel layout with the stability of micro-circuit forming and can be used for the processing of back-bonded display panels.

[0116] The above embodiments are used to illustrate the specific implementation ideas of the present invention. Without departing from the technical solution of three-dimensional preprocessing, three-dimensional contour registration, curvature adaptive trajectory generation, segmented overlapping, and detection feedback to form production data, any equivalent substitutions, simple modifications, or combinations made by those skilled in the art to local structures, parameter windows, or control steps should fall within the protection scope of the present invention.

[0117] Those skilled in the art, in conjunction with the contents of the specification and actual processing conditions, can make adaptive adjustments to the sensor type, fixture structure, silver paste system, dispensing control method, and testing items; if these adjustments follow the basic principles of this invention and are implemented using conventional means in this technical field, they should be considered reasonable extensions of the technical solution of this application.

[0118] This specification selects several embodiments for illustration to facilitate understanding of the principles, processes, and application scenarios of the present invention, and does not imply that the present invention can only be implemented according to the listed embodiments. Unless otherwise specified in the claims, the scope of protection of the present invention should be determined by the claims and their equivalents.

Claims

1. A method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits, characterized in that, include: Obtain the display panel screen marking points and terminal design data, establish the workpiece coordinate system and theoretical circuit model, roughen the first right-angle transition area and the second right-angle transition area of ​​the display panel, and clean the front terminal area and the back bonding area. The image data and 3D contour data of the display panel are collected. A single line template is generated based on the screen marking points and expanded into multiple original dispensing paths according to the number of terminals and the terminal spacing. The original dispensing paths are subjected to curvature partitioning and local compensation based on the 3D contour data to obtain an optimized dispensing path. The optimized dispensing path is registered with the theoretical circuit model to generate a 3D dispensing trajectory. Nano-silver paste circuits are prepared in segments along a three-dimensional dispensing trajectory, and overlapping joints are formed in the first and second right-angle transition zones. The nano-silver paste circuits are then cured and tested. Based on the test results, the three-dimensional dispensing trajectory and process parameters are corrected to obtain the final production data.

2. The method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits as described in claim 1, characterized in that, The acquisition of image data and 3D contour data from the display panel, and the generation of a single line template based on screen marker points, includes: The positions of at least two screen markers are acquired using a vision system, and the screen markers are mapped to the imported terminal design data. Based on the coordinate correspondence results, determine the arrangement direction of the front terminal pads, the number of terminals, the terminal spacing, and the correspondence of the back bonding pads; A single line template is generated for the corresponding front terminal pads and back bonding pads. The single line template includes a front overlap section, a first transition section, a side extension section, a second transition section, and a back bonding section. The template of a single line is copied in an array according to the terminal spacing, and the minimum spacing between adjacent lines is verified to obtain the original dispensing path of all lines.

3. The method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits as described in claim 2, characterized in that, The process of generating a single circuit template for corresponding front terminal pads and back bonding pads includes: The center line of the front terminal pad is used as the initial reference for the front overlap section, the side center line or the side preset conductive area is used as the guiding reference for the side extension section, and the center line of the back bonding pad is used as the termination reference for the back bonding section. A first transition section is provided between the front overlapping section and the side extension section, and a second transition section is provided between the side extension section and the back binding section, with the ends of each section being set as overlapping ends that can overlap.

4. The method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits as described in claim 1, characterized in that, The curvature partitioning and local compensation of the original dispensing path based on three-dimensional contour data includes: Select contour sampling points in the front, side, back, first right-angle transition zone, and second right-angle transition zone of the original dispensing path, and determine the curvature level of the current area based on the directional changes of adjacent contour points. Regions with high curvature levels are marked as high curvature transition regions, and regions with low curvature levels and continuous contours are marked as low curvature surface regions. In the high curvature transition zone, add path control points and reduce dispensing speed; in the low curvature surface zone, merge redundant control points and maintain continuous dispensing. The distance between the nozzle and the display panel is adjusted based on the change in the height of the three-dimensional contour to obtain an optimized dispensing path; The curvature level includes a low curvature surface area, a medium curvature buffer zone, a high curvature transition zone, and a local anomaly zone. The processor calls different parameter vectors according to the curvature level. The parameter vectors include at least the control point step distance, the upper limit of the target height change slope, the dispensing speed multiplier, and the dispensing amount per unit length multiplier, so that the same curvature partition result simultaneously constrains the trajectory shape and the amount of forming material.

5. The method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits as described in claim 4, characterized in that, The method of correcting the distance between the nozzle and the display panel based on the change in the height of the three-dimensional contour includes: Obtain the local normal direction and local height corresponding to each path control point; The height difference between adjacent control points is compared with a preset height change threshold. If the height difference exceeds the preset height change threshold, a transition control point is added between the adjacent control points. Set the target height of the nozzles at each control point to the sum of the local height and the preset distance from the surface; The nozzle target height of adjacent control points is smoothed to ensure that the electrohydrodynamic dispensing nozzle maintains continuous movement when passing through the first right-angle transition zone and the second right-angle transition zone. The smoothing process includes slope limiting or spline smoothing of the nozzle target height sequence to ensure that the height variation between adjacent control points does not exceed the height slope threshold. When the curvature level increases, the height slope threshold decreases, the density of path control points increases, the dispensing speed decreases, and the dispensing amount per unit length is adjusted simultaneously.

6. The method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits as described in claim 1, characterized in that, The roughening treatment of the first right-angle transition area and the second right-angle transition area of ​​the display panel, and the cleaning treatment of the front terminal area and the back bonding area, include: Laser cutting or laser roughening is performed on the terminal sides of polycrystalline silicon display panels or thin-film transistor display panels to achieve a surface roughness of 1.5μm to 2.5μm. Local energy trimming is performed on the first and second right-angle transition areas to ensure a continuous transition between the roughened side area and the front terminal area and the back bonding area, respectively. Plasma cleaning is performed on the front terminal area and the back bonding area, and the path collection or dispensing process is initiated within a preset waiting time after cleaning.

7. The method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits as described in claim 1, characterized in that, The process of optimizing the dispensing path and registering it with the theoretical circuit model to generate a three-dimensional dispensing trajectory includes: Terminal edge points, side edge points, and back bonding area edge points are extracted from the actual 3D contour data as actual feature points. Theoretical feature points corresponding to the actual feature points are extracted from the theoretical circuit model. The coordinate transformation relationship is obtained based on the actual feature points and the theoretical feature points. The original dispensing path is transformed to the actual contour position of the display panel. Lateral offset compensation, nozzle height compensation, dispensing volume compensation, and dispensing speed compensation are calculated for each line based on the transformed path position.

8. The method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits as described in claim 4, characterized in that, The segmented fabrication of nano-silver paste circuits along a three-dimensional dispensing trajectory includes: A front lap segment is prepared on the front terminal pad, so that the front lap segment covers the effective conductive area of ​​the corresponding terminal. A first transition segment is prepared along the first right-angle transition area, so that the end of the first transition segment and the front lap segment form an interleaved overlapping lap. A side extension segment is prepared along the side, and the side extension segment and the first transition segment are continuously conductive. A second transition segment is prepared along the second right-angle transition area, so that the end of the second transition segment and the side extension segment form an interleaved overlapping lap. A back bonding segment is prepared on the back bonding pad, so that the back bonding segment is connected to the second transition segment and the back bonding pad. In forming the overlapping joint, the processor generates a reduction dispensing coefficient based on the wet film state of the preceding line segment in the overlapping area, reducing the dispensing amount per unit length of the following line segment in the overlapping area to 55% to 85% of the dispensing amount per unit length of the adjacent non-overlapping area, or shortening the pulse width of the electro-hydraulic dispensing pulse.

9. The method for fabricating ultrafine and ultrathin nano-silver paste conductive circuits as described in claim 8, characterized in that, The overlap length of the staggered overlapping portion is 10μm to 80μm, the terminal spacing of the nano silver paste circuit is 50μm to 55μm, the line width is 30μm to 35μm, the thickness is 2μm to 5μm, the extension length of a single circuit from the front terminal pad to the back bonding pad is 0.4mm to 0.55mm, and the dispensing speed in the high curvature transition area is lower than the dispensing speed in the plane area where the front terminal pad is located or the plane area where the back bonding pad is located.

10. A system for fabricating ultra-fine and ultra-thin nano-silver paste conductive circuits, characterized in that, The device includes a positioning fixture, a vision acquisition unit, a three-dimensional contour acquisition unit, an electro-hydraulic dispensing unit, a detection feedback unit, a processor, and a memory. The memory stores a program that can be executed by the processor. When the processor executes the program, it controls the positioning fixture, the vision acquisition unit, the three-dimensional contour acquisition unit, the electro-hydraulic dispensing unit, and the detection feedback unit to perform the ultra-fine and ultra-thin nano silver paste conductive circuit processing method as described in any one of claims 1 to 9. The visual acquisition unit outputs the coordinates of the screen marking points, terminal edges, and the appearance of the cured lines to the processor. The three-dimensional contour acquisition unit outputs the height point cloud and normal data of the side and the two right-angle transition areas to the processor. The processor integrates the above data into three-dimensional trajectory points with curvature levels and sends the control point density, nozzle target height, dispensing speed, and dispensing amount per unit length of each three-dimensional trajectory point to the electro-hydraulic power dispensing unit. The detection feedback unit reverse-calculates the location of broken wires, short circuits, offsets, excessive thickness, or abnormal adhesion to the corresponding line number, line segment number, and trajectory point number. The processor updates the lateral offset, nozzle height, dispensing speed, dispensing volume, and overlap length compensation table within the correction range limited by the verification process window, and writes the updated compensation table together with the qualified trajectory into the final production data.

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